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    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:label="LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:title="LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" xlink:title="calculation: LesseeOperatingLeaseLiabilityPaymentsDue to LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFour" order="5.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:label="LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:title="LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" xlink:title="calculation: LesseeOperatingLeaseLiabilityPaymentsDue to LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearTwo" order="3.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:label="LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:title="LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" xlink:title="calculation: LesseeOperatingLeaseLiabilityPaymentsDue to LesseeOperatingLeaseLiabilityPaymentsDueNextRollingTwelveMonths" order="1.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:label="LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:title="LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" xlink:title="calculation: LesseeOperatingLeaseLiabilityPaymentsDue to LesseeOperatingLeaseLiabilityPaymentsDueInRollingYearFive" order="2.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiability" xlink:label="OperatingLeaseLiability" xlink:title="OperatingLeaseLiability" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="OperatingLeaseLiabilityCurrent" xlink:title="OperatingLeaseLiabilityCurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="OperatingLeaseLiability" xlink:to="OperatingLeaseLiabilityCurrent" xlink:title="calculation: OperatingLeaseLiability to OperatingLeaseLiabilityCurrent" order="0.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="OperatingLeaseLiabilityNoncurrent" xlink:title="OperatingLeaseLiabilityNoncurrent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="OperatingLeaseLiability" xlink:to="OperatingLeaseLiabilityNoncurrent" xlink:title="calculation: OperatingLeaseLiability to OperatingLeaseLiabilityNoncurrent" order="1.0" weight="1.0" />
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  <link:calculationLink xlink:type="extended" xlink:role="http://castormaritime.com/role/LeasesUndiscountedCashFlowsOfLeaseLiabilityDetailsCalc01">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="LesseeOperatingLeaseLiabilityPaymentsDue" xlink:title="LesseeOperatingLeaseLiabilityPaymentsDue" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:label="LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:title="LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="LesseeOperatingLeaseLiabilityPaymentsDue" xlink:to="LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:title="calculation: LesseeOperatingLeaseLiabilityPaymentsDue to LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" order="1.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiability" xlink:label="OperatingLeaseLiability" xlink:title="OperatingLeaseLiability" />
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  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://castormaritime.com/role/CommitmentsAndContingenciesCommitmentsUnderLongtermLeaseContractsDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceived" xlink:label="LessorOperatingLeasePaymentsToBeReceived" xlink:title="LessorOperatingLeasePaymentsToBeReceived" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" xlink:label="LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" xlink:title="LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="LessorOperatingLeasePaymentsToBeReceived" xlink:to="LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" xlink:title="calculation: LessorOperatingLeasePaymentsToBeReceived to LessorOperatingLeasePaymentsToBeReceivedNextRollingTwelveMonths" order="1.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" xlink:label="LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" xlink:title="LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="LessorOperatingLeasePaymentsToBeReceived" xlink:to="LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" xlink:title="calculation: LessorOperatingLeasePaymentsToBeReceived to LessorOperatingLeasePaymentsToBeReceivedRollingYearTwo" order="0.0" weight="1.0" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://castormaritime.com/role/EarningsPerCommonShareDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="WeightedAverageNumberOfDilutedSharesOutstanding" xlink:title="WeightedAverageNumberOfDilutedSharesOutstanding" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="WeightedAverageNumberOfSharesOutstandingBasic" xlink:title="WeightedAverageNumberOfSharesOutstandingBasic" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="WeightedAverageNumberOfSharesOutstandingBasic" xlink:title="calculation: WeightedAverageNumberOfDilutedSharesOutstanding to WeightedAverageNumberOfSharesOutstandingBasic" order="1.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:title="WeightedAverageNumberDilutedSharesOutstandingAdjustment" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="WeightedAverageNumberOfDilutedSharesOutstanding" xlink:to="WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:title="calculation: WeightedAverageNumberOfDilutedSharesOutstanding to WeightedAverageNumberDilutedSharesOutstandingAdjustment" order="0.0" weight="1.0" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://castormaritime.com/role/VesselOperatingExpensesAndVoyageExpensesDetails">
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_VoyageExpenses" xlink:label="VoyageExpenses" xlink:title="VoyageExpenses" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_BrokerageCommissions" xlink:label="BrokerageCommissions" xlink:title="BrokerageCommissions" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="VoyageExpenses" xlink:to="BrokerageCommissions" xlink:title="calculation: VoyageExpenses to BrokerageCommissions" order="0.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_BunkersConsumption" xlink:label="BunkersConsumption" xlink:title="BunkersConsumption" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="VoyageExpenses" xlink:to="BunkersConsumption" xlink:title="calculation: VoyageExpenses to BunkersConsumption" order="2.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_BrokerageCommissionsRelatedParty" xlink:label="BrokerageCommissionsRelatedParty" xlink:title="BrokerageCommissionsRelatedParty" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="VoyageExpenses" xlink:to="BrokerageCommissionsRelatedParty" xlink:title="calculation: VoyageExpenses to BrokerageCommissionsRelatedParty" order="4.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_PortAndOtherExpenses" xlink:label="PortAndOtherExpenses" xlink:title="PortAndOtherExpenses" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="VoyageExpenses" xlink:to="PortAndOtherExpenses" xlink:title="calculation: VoyageExpenses to PortAndOtherExpenses" order="1.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_LossGainOnBunkerFuel" xlink:label="LossGainOnBunkerFuel" xlink:title="LossGainOnBunkerFuel" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="VoyageExpenses" xlink:to="LossGainOnBunkerFuel" xlink:title="calculation: VoyageExpenses to LossGainOnBunkerFuel" order="3.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingCostsAndExpenses" xlink:label="OperatingCostsAndExpenses" xlink:title="OperatingCostsAndExpenses" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_VesselRepairAndMaintenanceExpenses" xlink:label="VesselRepairAndMaintenanceExpenses" xlink:title="VesselRepairAndMaintenanceExpenses" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="OperatingCostsAndExpenses" xlink:to="VesselRepairAndMaintenanceExpenses" xlink:title="calculation: OperatingCostsAndExpenses to VesselRepairAndMaintenanceExpenses" order="2.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxesExcludingIncomeAndExciseTaxes" xlink:label="TaxesExcludingIncomeAndExciseTaxes" xlink:title="TaxesExcludingIncomeAndExciseTaxes" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="OperatingCostsAndExpenses" xlink:to="TaxesExcludingIncomeAndExciseTaxes" xlink:title="calculation: OperatingCostsAndExpenses to TaxesExcludingIncomeAndExciseTaxes" order="5.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_LubricantExpenses" xlink:label="LubricantExpenses" xlink:title="LubricantExpenses" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="OperatingCostsAndExpenses" xlink:to="LubricantExpenses" xlink:title="calculation: OperatingCostsAndExpenses to LubricantExpenses" order="3.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCostAndExpenseOperating" xlink:label="OtherCostAndExpenseOperating" xlink:title="OtherCostAndExpenseOperating" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="OperatingCostsAndExpenses" xlink:to="OtherCostAndExpenseOperating" xlink:title="calculation: OperatingCostsAndExpenses to OtherCostAndExpenseOperating" order="6.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LaborAndRelatedExpense" xlink:label="LaborAndRelatedExpense" xlink:title="LaborAndRelatedExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="OperatingCostsAndExpenses" xlink:to="LaborAndRelatedExpense" xlink:title="calculation: OperatingCostsAndExpenses to LaborAndRelatedExpense" order="1.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralInsuranceExpense" xlink:label="GeneralInsuranceExpense" xlink:title="GeneralInsuranceExpense" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="OperatingCostsAndExpenses" xlink:to="GeneralInsuranceExpense" xlink:title="calculation: OperatingCostsAndExpenses to GeneralInsuranceExpense" order="4.0" weight="1.0" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://castormaritime.com/role/GeneralAndAdministrativeExpensesDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="GeneralAndAdministrativeExpense" xlink:title="GeneralAndAdministrativeExpense" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OfficersCompensation" xlink:label="OfficersCompensation" xlink:title="OfficersCompensation" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="GeneralAndAdministrativeExpense" xlink:to="OfficersCompensation" xlink:title="calculation: GeneralAndAdministrativeExpense to OfficersCompensation" order="0.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProfessionalFees" xlink:label="ProfessionalFees" xlink:title="ProfessionalFees" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="GeneralAndAdministrativeExpense" xlink:to="ProfessionalFees" xlink:title="calculation: GeneralAndAdministrativeExpense to ProfessionalFees" order="3.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_DirectorFees" xlink:label="DirectorFees" xlink:title="DirectorFees" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="GeneralAndAdministrativeExpense" xlink:to="DirectorFees" xlink:title="calculation: GeneralAndAdministrativeExpense to DirectorFees" order="4.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_OfficeAndTechnologyExpensesIncludingRent" xlink:label="OfficeAndTechnologyExpensesIncludingRent" xlink:title="OfficeAndTechnologyExpensesIncludingRent" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="GeneralAndAdministrativeExpense" xlink:to="OfficeAndTechnologyExpensesIncludingRent" xlink:title="calculation: GeneralAndAdministrativeExpense to OfficeAndTechnologyExpensesIncludingRent" order="6.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_PersonnelExpenses" xlink:label="PersonnelExpenses" xlink:title="PersonnelExpenses" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="GeneralAndAdministrativeExpense" xlink:to="PersonnelExpenses" xlink:title="calculation: GeneralAndAdministrativeExpense to PersonnelExpenses" order="5.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_RelatedPartyTransactionFlatManagementFees" xlink:label="RelatedPartyTransactionFlatManagementFees" xlink:title="RelatedPartyTransactionFlatManagementFees" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="GeneralAndAdministrativeExpense" xlink:to="RelatedPartyTransactionFlatManagementFees" xlink:title="calculation: GeneralAndAdministrativeExpense to RelatedPartyTransactionFlatManagementFees" order="8.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation" xlink:label="ShareBasedCompensation" xlink:title="ShareBasedCompensation" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="GeneralAndAdministrativeExpense" xlink:to="ShareBasedCompensation" xlink:title="calculation: GeneralAndAdministrativeExpense to ShareBasedCompensation" order="7.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_AuditFees" xlink:label="AuditFees" xlink:title="AuditFees" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="GeneralAndAdministrativeExpense" xlink:to="AuditFees" xlink:title="calculation: GeneralAndAdministrativeExpense to AuditFees" order="2.0" weight="1.0" />
  </link:calculationLink>
  <link:calculationLink xlink:type="extended" xlink:role="http://castormaritime.com/role/CostOfRevenueFromServicesDetails">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization" xlink:label="CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization" xlink:title="CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization" />
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostDirectLabor" xlink:label="CostDirectLabor" xlink:title="CostDirectLabor" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization" xlink:to="CostDirectLabor" xlink:title="calculation: CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization to CostDirectLabor" order="0.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_CostOfCommissions" xlink:label="CostOfCommissions" xlink:title="CostOfCommissions" />
    <link:calculationArc xlink:type="arc" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization" xlink:to="CostOfCommissions" xlink:title="calculation: CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization to CostOfCommissions" order="3.0" weight="1.0" />
    <link:loc xlink:type="locator" xlink:href="ctrm-20260630.xsd#ctrm_CostOfPurchasedServices" xlink:label="CostOfPurchasedServices" xlink:title="CostOfPurchasedServices" />
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