<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
<!--Generated by ThunderDome XBRL - 06:09PM UTC 2024-05-10--><link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-7-leases-schedule-of-maturity-for-operating-leases-details" xlink:href="fsbw-20240331.xsd#statement-note-7-leases-schedule-of-maturity-for-operating-leases-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-7-leases-schedule-of-maturity-for-operating-leases-details" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" xlink:label="fsbw_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear" xlink:label="us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="fsbw_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:type="arc"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-9-deposits-schedule-of-maturity-details" xlink:href="fsbw-20240331.xsd#statement-note-9-deposits-schedule-of-maturity-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-9-deposits-schedule-of-maturity-details" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_TimeDepositMaturitiesAfterYearFour" xlink:label="fsbw_TimeDepositMaturitiesAfterYearFour" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeDepositMaturitiesRemainderOfFiscalYear" xlink:label="us-gaap_TimeDepositMaturitiesRemainderOfFiscalYear" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeDepositMaturitiesYearFour" xlink:label="us-gaap_TimeDepositMaturitiesYearFour" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeDepositMaturitiesYearOne" xlink:label="us-gaap_TimeDepositMaturitiesYearOne" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeDepositMaturitiesYearThree" xlink:label="us-gaap_TimeDepositMaturitiesYearThree" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeDepositMaturitiesYearTwo" xlink:label="us-gaap_TimeDepositMaturitiesYearTwo" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeDeposits" xlink:label="us-gaap_TimeDeposits" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_TimeDeposits" xlink:to="fsbw_TimeDepositMaturitiesAfterYearFour" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_TimeDeposits" xlink:to="us-gaap_TimeDepositMaturitiesYearFour" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_TimeDeposits" xlink:to="us-gaap_TimeDepositMaturitiesYearOne" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_TimeDeposits" xlink:to="us-gaap_TimeDepositMaturitiesRemainderOfFiscalYear" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_TimeDeposits" xlink:to="us-gaap_TimeDepositMaturitiesYearThree" xlink:type="arc"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_TimeDeposits" xlink:to="us-gaap_TimeDepositMaturitiesYearTwo" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-16-goodwill-and-other-intangible-assets-schedule-of-amortization-details" xlink:href="fsbw-20240331.xsd#statement-note-16-goodwill-and-other-intangible-assets-schedule-of-amortization-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-16-goodwill-and-other-intangible-assets-schedule-of-amortization-details" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_FinitelivedIntangibleAssetExpectedAmortizationAfterYearFour" xlink:label="fsbw_FinitelivedIntangibleAssetExpectedAmortizationAfterYearFour" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear" xlink:type="arc"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:to="fsbw_FinitelivedIntangibleAssetExpectedAmortizationAfterYearFour" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-consolidated-balance-sheets-current-period-unaudited" xlink:href="fsbw-20240331.xsd#statement-consolidated-balance-sheets-current-period-unaudited" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-consolidated-balance-sheets-current-period-unaudited" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_MortgageServicingAssetHeldForSale" xlink:label="fsbw_MortgageServicingAssetHeldForSale" xlink:type="locator"/>
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_SubordinatedDebtNetOfUnamortizedDebtIssuanceExpense" xlink:label="fsbw_SubordinatedDebtNetOfUnamortizedDebtIssuanceExpense" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="us-gaap_AdditionalPaidInCapital" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Assets" xlink:label="us-gaap_Assets" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BankOwnedLifeInsurance" xlink:label="us-gaap_BankOwnedLifeInsurance" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndDueFromBanks" xlink:label="us-gaap_CashAndDueFromBanks" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CertificatesOfDepositAtCarryingValue" xlink:label="us-gaap_CertificatesOfDepositAtCarryingValue" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="us-gaap_CommitmentsAndContingencies" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockValue" xlink:label="us-gaap_CommonStockValue" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss" xlink:label="us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredIncomeTaxAssetsNet" xlink:label="us-gaap_DeferredIncomeTaxAssetsNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Deposits" xlink:label="us-gaap_Deposits" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FederalHomeLoanBankStock" xlink:label="us-gaap_FederalHomeLoanBankStock" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestBearingDepositLiabilities" xlink:label="us-gaap_InterestBearingDepositLiabilities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestBearingDepositsInBanks" xlink:label="us-gaap_InterestBearingDepositsInBanks" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestReceivable" xlink:label="us-gaap_InterestReceivable" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Liabilities" xlink:label="us-gaap_Liabilities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LoansHeldForSaleFairValueDisclosure" xlink:label="us-gaap_LoansHeldForSaleFairValueDisclosure" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoninterestBearingDepositLiabilities" xlink:label="us-gaap_NoninterestBearingDepositLiabilities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NotesReceivableNet" xlink:label="us-gaap_NotesReceivableNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseLiability" xlink:label="us-gaap_OperatingLeaseLiability" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherAssets" xlink:label="us-gaap_OtherAssets" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherLiabilities" xlink:label="us-gaap_OtherLiabilities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PreferredStockValue" xlink:label="us-gaap_PreferredStockValue" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ServicingAsset" xlink:label="us-gaap_ServicingAsset" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermBorrowings" xlink:label="us-gaap_ShortTermBorrowings" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubordinatedDebt" xlink:label="us-gaap_SubordinatedDebt" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnamortizedDebtIssuanceExpense" xlink:label="us-gaap_UnamortizedDebtIssuanceExpense" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:to="us-gaap_CashAndDueFromBanks" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:to="us-gaap_InterestBearingDepositsInBanks" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_ServicingAsset" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="fsbw_MortgageServicingAssetHeldForSale" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_DeferredIncomeTaxAssetsNet" xlink:type="arc"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_CertificatesOfDepositAtCarryingValue" xlink:type="arc"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_BankOwnedLifeInsurance" xlink:type="arc"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_OtherAssets" xlink:type="arc"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_Goodwill" xlink:type="arc"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss" xlink:type="arc"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet" xlink:type="arc"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_LoansHeldForSaleFairValueDisclosure" xlink:type="arc"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_NotesReceivableNet" xlink:type="arc"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset" xlink:type="arc"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_FederalHomeLoanBankStock" xlink:type="arc"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_InterestReceivable" xlink:type="arc"/>
    <link:calculationArc order="16" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Assets" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_InterestBearingDepositLiabilities" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_NoninterestBearingDepositLiabilities" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="fsbw_SubordinatedDebtNetOfUnamortizedDebtIssuanceExpense" xlink:to="us-gaap_SubordinatedDebt" xlink:type="arc"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="fsbw_SubordinatedDebtNetOfUnamortizedDebtIssuanceExpense" xlink:to="us-gaap_UnamortizedDebtIssuanceExpense" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_OtherLiabilities" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_Deposits" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="fsbw_SubordinatedDebtNetOfUnamortizedDebtIssuanceExpense" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_OperatingLeaseLiability" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_ShortTermBorrowings" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_CommonStockValue" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_AdditionalPaidInCapital" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_PreferredStockValue" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_Liabilities" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_StockholdersEquity" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_CommitmentsAndContingencies" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-2-business-combination-estimated-fair-value-of-assets-acquired-and-liabilities-assumed-details" xlink:href="fsbw-20240331.xsd#statement-note-2-business-combination-estimated-fair-value-of-assets-acquired-and-liabilities-assumed-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-2-business-combination-estimated-fair-value-of-assets-acquired-and-liabilities-assumed-details" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAdjustmentsDepositsTotal" xlink:label="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAdjustmentsDepositsTotal" xlink:type="locator"/>
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAdjustmentsReceivables" xlink:label="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAdjustmentsReceivables" xlink:type="locator"/>
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAccruedInterestReceivables" xlink:label="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAccruedInterestReceivables" xlink:type="locator"/>
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAccruedInterestPayable" xlink:label="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAccruedInterestPayable" xlink:type="locator"/>
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesDepositsTotal" xlink:label="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesDepositsTotal" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill" xlink:label="us-gaap_Goodwill" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="us-gaap_Goodwill" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsAccruedInterestReceivables" xlink:type="arc"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:type="arc"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:type="arc"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:to="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAdjustmentsReceivables" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:to="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAccruedInterestPayable" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:to="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesDepositsTotal" xlink:type="arc"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:to="fsbw_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAdjustmentsDepositsTotal" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-consolidated-statements-of-cash-flows-unaudited" xlink:href="fsbw-20240331.xsd#statement-consolidated-statements-of-cash-flows-unaudited" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-consolidated-statements-of-cash-flows-unaudited" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_GainLossOnDispositionOfMortgageServicingRightsMsr" xlink:label="fsbw_GainLossOnDispositionOfMortgageServicingRightsMsr" xlink:type="locator"/>
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_GainLossOnSaleOfLoansHeldForSale" xlink:label="fsbw_GainLossOnSaleOfLoansHeldForSale" xlink:type="locator"/>
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_PaymentsForOriginationOfLoansAndPrincipleCollectionsNet" xlink:label="fsbw_PaymentsForOriginationOfLoansAndPrincipleCollectionsNet" xlink:type="locator"/>
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_ProceedsDisbursementsFromStockOptionsExercised" xlink:label="fsbw_ProceedsDisbursementsFromStockOptionsExercised" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAcquiredFromAcquisition" xlink:label="us-gaap_CashAcquiredFromAcquisition" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:label="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtAndEquitySecuritiesRealizedGainLoss" xlink:label="us-gaap_DebtAndEquitySecuritiesRealizedGainLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DepreciationAmortizationAndAccretionNet" xlink:label="us-gaap_DepreciationAmortizationAndAccretionNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet" xlink:label="us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInDeposits" xlink:label="us-gaap_IncreaseDecreaseInDeposits" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:label="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue" xlink:label="us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MortgageServicingRightsMSRImpairmentRecovery" xlink:label="us-gaap_MortgageServicingRightsMSRImpairmentRecovery" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForOriginationOfMortgageLoansHeldForSale" xlink:label="us-gaap_PaymentsForOriginationOfMortgageLoansHeldForSale" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock" xlink:label="us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsOfDividendsCommonStock" xlink:label="us-gaap_PaymentsOfDividendsCommonStock" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt" xlink:label="us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireLoansHeldForInvestment" xlink:label="us-gaap_PaymentsToAcquireLoansHeldForInvestment" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsToAcquireRestrictedCertificatesOfDeposit" xlink:label="us-gaap_PaymentsToAcquireRestrictedCertificatesOfDeposit" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromFederalHomeLoanBankBorrowings" xlink:label="us-gaap_ProceedsFromFederalHomeLoanBankBorrowings" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" xlink:label="us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromPaymentsForInInterestBearingDepositsInBanks" xlink:label="us-gaap_ProceedsFromPaymentsForInInterestBearingDepositsInBanks" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" xlink:label="us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromSaleOfLoansHeldForSale" xlink:label="us-gaap_ProceedsFromSaleOfLoansHeldForSale" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromSaleOfMortgageServicingRightsMSR" xlink:label="us-gaap_ProceedsFromSaleOfMortgageServicingRightsMSR" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromStockPlans" xlink:label="us-gaap_ProceedsFromStockPlans" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProvisionForLoanLeaseAndOtherLosses" xlink:label="us-gaap_ProvisionForLoanLeaseAndOtherLosses" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfFederalHomeLoanBankBorrowings" xlink:label="us-gaap_RepaymentsOfFederalHomeLoanBankBorrowings" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation" xlink:label="us-gaap_ShareBasedCompensation" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_ShareBasedCompensation" xlink:type="arc"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_LifeInsuranceCorporateOrBankOwnedChangeInValue" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_ProvisionForLoanLeaseAndOtherLosses" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_DepreciationAmortizationAndAccretionNet" xlink:type="arc"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_DebtAndEquitySecuritiesRealizedGainLoss" xlink:type="arc"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_PaymentsForOriginationOfMortgageLoansHeldForSale" xlink:type="arc"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="fsbw_GainLossOnSaleOfLoansHeldForSale" xlink:type="arc"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="fsbw_GainLossOnDispositionOfMortgageServicingRightsMsr" xlink:type="arc"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet" xlink:type="arc"/>
    <link:calculationArc order="9" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:type="arc"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_ProceedsFromSaleOfLoansHeldForSale" xlink:type="arc"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_MortgageServicingRightsMSRImpairmentRecovery" xlink:type="arc"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_NetIncomeLoss" xlink:type="arc"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:to="us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_ProceedsFromPaymentsForInInterestBearingDepositsInBanks" xlink:type="arc"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_PaymentsToAcquireRestrictedCertificatesOfDeposit" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities" xlink:type="arc"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="arc"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt" xlink:type="arc"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock" xlink:type="arc"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_ProceedsFromSaleOfMortgageServicingRightsMSR" xlink:type="arc"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" xlink:type="arc"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_PaymentsToAcquireLoansHeldForInvestment" xlink:type="arc"/>
    <link:calculationArc order="9" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="fsbw_PaymentsForOriginationOfLoansAndPrincipleCollectionsNet" xlink:type="arc"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:to="us-gaap_CashAcquiredFromAcquisition" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromStockPlans" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="fsbw_ProceedsDisbursementsFromStockOptionsExercised" xlink:type="arc"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:type="arc"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_RepaymentsOfFederalHomeLoanBankBorrowings" xlink:type="arc"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_PaymentsOfDividendsCommonStock" xlink:type="arc"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_IncreaseDecreaseInDeposits" xlink:type="arc"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:to="us-gaap_ProceedsFromFederalHomeLoanBankBorrowings" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-4-loans-receivable-and-allowance-for-credit-losses-on-loans-schedule-of-portfolio-loan-composition-details" xlink:href="fsbw-20240331.xsd#statement-note-4-loans-receivable-and-allowance-for-credit-losses-on-loans-schedule-of-portfolio-loan-composition-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-4-loans-receivable-and-allowance-for-credit-losses-on-loans-schedule-of-portfolio-loan-composition-details" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancingReceivableAllowanceForCreditLosses" xlink:label="us-gaap_FinancingReceivableAllowanceForCreditLosses" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NotesReceivableGross" xlink:label="us-gaap_NotesReceivableGross" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NotesReceivableNet" xlink:label="us-gaap_NotesReceivableNet" xlink:type="locator"/>
    <link:calculationArc order="0" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NotesReceivableNet" xlink:to="us-gaap_FinancingReceivableAllowanceForCreditLosses" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NotesReceivableNet" xlink:to="us-gaap_NotesReceivableGross" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-7-leases-schedule-of-lease-cost-details" xlink:href="fsbw-20240331.xsd#statement-note-7-leases-schedule-of-lease-cost-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-7-leases-schedule-of-lease-cost-details" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LeaseCost" xlink:label="us-gaap_LeaseCost" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseCost" xlink:label="us-gaap_OperatingLeaseCost" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermLeaseCost" xlink:label="us-gaap_ShortTermLeaseCost" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LeaseCost" xlink:to="us-gaap_ShortTermLeaseCost" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_LeaseCost" xlink:to="us-gaap_OperatingLeaseCost" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-9-deposits-schedule-of-deposit-liabilities-details" xlink:href="fsbw-20240331.xsd#statement-note-9-deposits-schedule-of-deposit-liabilities-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-9-deposits-schedule-of-deposit-liabilities-details" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_NoninterestbearingDepositEscrowForMortgagesServiced" xlink:label="fsbw_NoninterestbearingDepositEscrowForMortgagesServiced" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Deposits" xlink:label="us-gaap_Deposits" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DepositsMoneyMarketDeposits" xlink:label="us-gaap_DepositsMoneyMarketDeposits" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DepositsSavingsDeposits" xlink:label="us-gaap_DepositsSavingsDeposits" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestBearingDomesticDepositChecking" xlink:label="us-gaap_InterestBearingDomesticDepositChecking" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoninterestBearingDomesticDepositChecking" xlink:label="us-gaap_NoninterestBearingDomesticDepositChecking" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeDeposits100000OrMore" xlink:label="us-gaap_TimeDeposits100000OrMore" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit" xlink:label="us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TimeDepositsLessThan100000" xlink:label="us-gaap_TimeDepositsLessThan100000" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="fsbw_NoninterestbearingDepositEscrowForMortgagesServiced" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_NoninterestBearingDomesticDepositChecking" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_TimeDeposits100000OrMore" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_DepositsMoneyMarketDeposits" xlink:type="arc"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_TimeDepositsLessThan100000" xlink:type="arc"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_InterestBearingDomesticDepositChecking" xlink:type="arc"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_Deposits" xlink:to="us-gaap_DepositsSavingsDeposits" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-11-fair-value-measurements-schedule-of-financial-assets-and-liabilities-on-a-recurring-basis-details" xlink:href="fsbw-20240331.xsd#statement-note-11-fair-value-measurements-schedule-of-financial-assets-and-liabilities-on-a-recurring-basis-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-11-fair-value-measurements-schedule-of-financial-assets-and-liabilities-on-a-recurring-basis-details" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="us-gaap_AssetsFairValueDisclosure" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssets" xlink:label="us-gaap_DerivativeAssets" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilities" xlink:label="us-gaap_DerivativeLiabilities" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure" xlink:label="us-gaap_FinancialLiabilitiesFairValueDisclosure" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LoansHeldForSaleFairValueDisclosure" xlink:label="us-gaap_LoansHeldForSaleFairValueDisclosure" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MortgagesHeldForSaleFairValueDisclosure" xlink:label="us-gaap_MortgagesHeldForSaleFairValueDisclosure" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsFairValueDisclosure" xlink:to="us-gaap_DerivativeAssets" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsFairValueDisclosure" xlink:to="us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsFairValueDisclosure" xlink:to="us-gaap_MortgagesHeldForSaleFairValueDisclosure" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsFairValueDisclosure" xlink:to="us-gaap_LoansHeldForSaleFairValueDisclosure" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_FinancialLiabilitiesFairValueDisclosure" xlink:to="us-gaap_DerivativeLiabilities" xlink:type="arc"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_AssetsFairValueDisclosure" xlink:to="us-gaap_DerivativeLiabilities" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-12-earnings-per-share-schedule-of-earnings-per-share-details" xlink:href="fsbw-20240331.xsd#statement-note-12-earnings-per-share-schedule-of-earnings-per-share-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-12-earnings-per-share-schedule-of-earnings-per-share-details" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:label="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic" xlink:label="us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:to="us-gaap_NetIncomeLoss" xlink:type="arc"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic" xlink:to="us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-15-business-segments-schedule-of-segment-financial-results-details" xlink:href="fsbw-20240331.xsd#statement-note-15-business-segments-schedule-of-segment-financial-results-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-15-business-segments-schedule-of-segment-financial-results-details" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestIncomeExpenseNet" xlink:label="us-gaap_InterestIncomeExpenseNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoninterestExpense" xlink:label="us-gaap_NoninterestExpense" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoninterestIncome" xlink:label="us-gaap_NoninterestIncome" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProvisionForLoanLeaseAndOtherLosses" xlink:label="us-gaap_ProvisionForLoanLeaseAndOtherLosses" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_InterestIncomeExpenseNet" xlink:type="arc"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_NoninterestExpense" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_NoninterestIncome" xlink:type="arc"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_ProvisionForLoanLeaseAndOtherLosses" xlink:type="arc"/>
    <link:calculationArc order="0" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_IncomeTaxExpenseBenefit" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-consolidated-statements-of-income-unaudited" xlink:href="fsbw-20240331.xsd#statement-consolidated-statements-of-income-unaudited" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-consolidated-statements-of-income-unaudited" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_GainLossOnDispositionOfMortgageServicingRightsMsr" xlink:label="fsbw_GainLossOnDispositionOfMortgageServicingRightsMsr" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="us-gaap_AmortizationOfIntangibleAssets" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BankOwnedLifeInsuranceIncome" xlink:label="us-gaap_BankOwnedLifeInsuranceIncome" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:label="us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtAndEquitySecuritiesRealizedGainLoss" xlink:label="us-gaap_DebtAndEquitySecuritiesRealizedGainLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FederalDepositInsuranceCorporationPremiumExpense" xlink:label="us-gaap_FederalDepositInsuranceCorporationPremiumExpense" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FeeIncome" xlink:label="us-gaap_FeeIncome" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainLossOnSalesOfLoansNet" xlink:label="us-gaap_GainLossOnSalesOfLoansNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InformationTechnologyAndDataProcessing" xlink:label="us-gaap_InformationTechnologyAndDataProcessing" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestAndDividendIncomeOperating" xlink:label="us-gaap_InterestAndDividendIncomeOperating" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestAndFeeIncomeLoansAndLeases" xlink:label="us-gaap_InterestAndFeeIncomeLoansAndLeases" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpense" xlink:label="us-gaap_InterestExpense" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseDeposits" xlink:label="us-gaap_InterestExpenseDeposits" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseFederalHomeLoanBankAndFederalReserveBankAdvancesLongTerm" xlink:label="us-gaap_InterestExpenseFederalHomeLoanBankAndFederalReserveBankAdvancesLongTerm" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseSubordinatedNotesAndDebentures" xlink:label="us-gaap_InterestExpenseSubordinatedNotesAndDebentures" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss" xlink:label="us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestIncomeExpenseNet" xlink:label="us-gaap_InterestIncomeExpenseNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InvestmentIncomeInterestAndDividend" xlink:label="us-gaap_InvestmentIncomeInterestAndDividend" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LaborAndRelatedExpense" xlink:label="us-gaap_LaborAndRelatedExpense" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LoanProcessingFee" xlink:label="us-gaap_LoanProcessingFee" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MarketingAndAdvertisingExpense" xlink:label="us-gaap_MarketingAndAdvertisingExpense" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MortgageServicingRightsMSRImpairmentRecovery" xlink:label="us-gaap_MortgageServicingRightsMSRImpairmentRecovery" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoninterestExpense" xlink:label="us-gaap_NoninterestExpense" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoninterestIncome" xlink:label="us-gaap_NoninterestIncome" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoninterestIncomeOther" xlink:label="us-gaap_NoninterestIncomeOther" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OccupancyNet" xlink:label="us-gaap_OccupancyNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfessionalFees" xlink:label="us-gaap_ProfessionalFees" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProvisionForLoanLeaseAndOtherLosses" xlink:label="us-gaap_ProvisionForLoanLeaseAndOtherLosses" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestAndDividendIncomeOperating" xlink:to="us-gaap_InterestAndFeeIncomeLoansAndLeases" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestAndDividendIncomeOperating" xlink:to="us-gaap_InvestmentIncomeInterestAndDividend" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestExpense" xlink:to="us-gaap_InterestExpenseSubordinatedNotesAndDebentures" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestExpense" xlink:to="us-gaap_InterestExpenseDeposits" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestExpense" xlink:to="us-gaap_InterestExpenseFederalHomeLoanBankAndFederalReserveBankAdvancesLongTerm" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestIncomeExpenseNet" xlink:to="us-gaap_InterestAndDividendIncomeOperating" xlink:type="arc"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestIncomeExpenseNet" xlink:to="us-gaap_InterestExpense" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss" xlink:to="us-gaap_InterestIncomeExpenseNet" xlink:type="arc"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss" xlink:to="us-gaap_ProvisionForLoanLeaseAndOtherLosses" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestIncome" xlink:to="us-gaap_FeeIncome" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestIncome" xlink:to="us-gaap_NoninterestIncomeOther" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestIncome" xlink:to="us-gaap_DebtAndEquitySecuritiesRealizedGainLoss" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestIncome" xlink:to="us-gaap_BankOwnedLifeInsuranceIncome" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestIncome" xlink:to="us-gaap_GainLossOnSalesOfLoansNet" xlink:type="arc"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestIncome" xlink:to="fsbw_GainLossOnDispositionOfMortgageServicingRightsMsr" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_MarketingAndAdvertisingExpense" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_LaborAndRelatedExpense" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_BusinessCombinationAcquisitionRelatedCosts" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_ProfessionalFees" xlink:type="arc"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_FederalDepositInsuranceCorporationPremiumExpense" xlink:type="arc"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_InformationTechnologyAndDataProcessing" xlink:type="arc"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_LoanProcessingFee" xlink:type="arc"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:type="arc"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_AmortizationOfIntangibleAssets" xlink:type="arc"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_OccupancyNet" xlink:type="arc"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestExpense" xlink:to="us-gaap_MortgageServicingRightsMSRImpairmentRecovery" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_NoninterestIncome" xlink:type="arc"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_NoninterestExpense" xlink:type="arc"/>
    <link:calculationArc order="0" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_IncomeTaxExpenseBenefit" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-consolidated-statements-of-comprehensive-income-unaudited" xlink:href="fsbw-20240331.xsd#statement-consolidated-statements-of-comprehensive-income-unaudited" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-consolidated-statements-of-comprehensive-income-unaudited" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss" xlink:label="us-gaap_NetIncomeLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax" xlink:label="us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax" xlink:type="locator"/>
    <link:calculationArc order="0" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax" xlink:type="arc"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationTax" xlink:type="arc"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax" xlink:type="arc"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax" xlink:type="arc"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" xlink:type="arc"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax" xlink:type="arc"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" xlink:type="arc"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_ComprehensiveIncomeNetOfTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_ComprehensiveIncomeNetOfTax" xlink:to="us-gaap_NetIncomeLoss" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-4-loans-receivable-and-allowance-for-credit-losses-on-loans-schedule-of-allowance-for-credit-losses-by-category-details" xlink:href="fsbw-20240331.xsd#statement-note-4-loans-receivable-and-allowance-for-credit-losses-on-loans-schedule-of-allowance-for-credit-losses-by-category-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-4-loans-receivable-and-allowance-for-credit-losses-on-loans-schedule-of-allowance-for-credit-losses-by-category-details" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffAfterRecovery" xlink:label="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffAfterRecovery" xlink:type="locator"/>
    <link:calculationArc order="0" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffAfterRecovery" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossRecovery" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoffAfterRecovery" xlink:to="us-gaap_FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-9-deposits-schedule-interest-expense-by-category-details" xlink:href="fsbw-20240331.xsd#statement-note-9-deposits-schedule-interest-expense-by-category-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-9-deposits-schedule-interest-expense-by-category-details" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_InterestExpenseMoneyMarketAccountsAndSavingsDeposits" xlink:label="fsbw_InterestExpenseMoneyMarketAccountsAndSavingsDeposits" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseDeposits" xlink:label="us-gaap_InterestExpenseDeposits" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit" xlink:label="us-gaap_InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpenseDomesticDepositLiabilitiesChecking" xlink:label="us-gaap_InterestExpenseDomesticDepositLiabilitiesChecking" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestExpenseDeposits" xlink:to="us-gaap_InterestExpenseDomesticDepositLiabilitiesChecking" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestExpenseDeposits" xlink:to="fsbw_InterestExpenseMoneyMarketAccountsAndSavingsDeposits" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_InterestExpenseDeposits" xlink:to="us-gaap_InterestExpenseDomesticDepositLiabilitiesCertificatesOfDeposit" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-17-revenue-from-contracts-with-customers-schedule-of-noninterest-income-details" xlink:href="fsbw-20240331.xsd#statement-note-17-revenue-from-contracts-with-customers-schedule-of-noninterest-income-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-17-revenue-from-contracts-with-customers-schedule-of-noninterest-income-details" xlink:type="extended">
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NoninterestIncome" xlink:label="us-gaap_NoninterestIncome" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueNotFromContractWithCustomerExcludingInterestIncome" xlink:label="us-gaap_RevenueNotFromContractWithCustomerExcludingInterestIncome" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestIncome" xlink:to="us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_NoninterestIncome" xlink:to="us-gaap_RevenueNotFromContractWithCustomerExcludingInterestIncome" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://investorrelations.fsbwa.com/20240331/role/statement-note-6-derivatives-schedule-of-hedging-relationship-details" xlink:href="fsbw-20240331.xsd#statement-note-6-derivatives-schedule-of-hedging-relationship-details" xlink:type="simple"/>
  <link:calculationLink xlink:role="http://investorrelations.fsbwa.com/20240331/role/statement-note-6-derivatives-schedule-of-hedging-relationship-details" xlink:type="extended">
    <link:loc xlink:href="fsbw-20240331.xsd#fsbw_NetInterestIncomeExpenseRecognizedOnCashFlowsOfDerivitiesDesignatedAsHedgingInstruments" xlink:label="fsbw_NetInterestIncomeExpenseRecognizedOnCashFlowsOfDerivitiesDesignatedAsHedgingInstruments" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1" xlink:label="us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1" xlink:label="us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss" xlink:label="us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainLossOnCashFlowHedgeIneffectivenessNet" xlink:label="us-gaap_GainLossOnCashFlowHedgeIneffectivenessNet" xlink:type="locator"/>
    <link:loc xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" xlink:label="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" xlink:type="locator"/>
    <link:calculationArc order="0" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss" xlink:to="fsbw_NetInterestIncomeExpenseRecognizedOnCashFlowsOfDerivitiesDesignatedAsHedgingInstruments" xlink:type="arc"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss" xlink:to="us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments1" xlink:type="arc"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_DerivativeFairValueHedgeIncludedInEffectivenessGainLoss" xlink:to="us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1" xlink:type="arc"/>
    <link:calculationArc order="0" weight="-1.0" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="us-gaap_GainLossOnCashFlowHedgeIneffectivenessNet" xlink:to="us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
