<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019e03ad-6fa3-7814-b65a-98bdb62ae5cc,g:d600c8ee-d387-49ed-9e86-8e2dd02158bd-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" 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:arcroleRef arcroleURI="https://xbrl.org/2023/arcrole/summation-item" xlink:type="simple" xlink:href="https://www.xbrl.org/2023/calculation-1.1.xsd#summation-item"/>
  <link:roleRef roleURI="http://www.billiontoone.com/role/BalanceSheets" xlink:type="simple" xlink:href="blln-20260630.xsd#BalanceSheets"/>
  <link:calculationLink xlink:role="http://www.billiontoone.com/role/BalanceSheets" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019e03ad-7076-796a-bcbd-acf536776fdd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019e03ad-7076-7dcf-ad4a-78740c23b08d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e03ad-7076-796a-bcbd-acf536776fdd" xlink:to="loc_us-gaap_AssetsCurrent_019e03ad-7076-7dcf-ad4a-78740c23b08d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019e03ad-7076-7247-a6e0-4b0de7f01913" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e03ad-7076-796a-bcbd-acf536776fdd" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019e03ad-7076-7247-a6e0-4b0de7f01913" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019e03ad-7076-76be-8ac9-4977e6a9c8ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e03ad-7076-796a-bcbd-acf536776fdd" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019e03ad-7076-76be-8ac9-4977e6a9c8ab" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_019e03ad-7076-7608-9fdd-0f7d9b2d307d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019e03ad-7076-796a-bcbd-acf536776fdd" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_019e03ad-7076-7608-9fdd-0f7d9b2d307d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7fd1-beaa-6e7bb4bc9b6a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019e03ad-7076-7d50-8e8b-49d51a895bee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7fd1-beaa-6e7bb4bc9b6a" xlink:to="loc_us-gaap_AccountsPayableCurrent_019e03ad-7076-7d50-8e8b-49d51a895bee" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccountsPayableAndAccruedLiabilities_019e03ad-7076-77c4-b8a6-bacdcc6db0b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAccountsPayableAndAccruedLiabilities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7fd1-beaa-6e7bb4bc9b6a" xlink:to="loc_us-gaap_OtherAccountsPayableAndAccruedLiabilities_019e03ad-7076-77c4-b8a6-bacdcc6db0b3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedSalesCommissionCurrent_019e03ad-7076-730b-8a6e-06c80cda5ccf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedSalesCommissionCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7fd1-beaa-6e7bb4bc9b6a" xlink:to="loc_us-gaap_AccruedSalesCommissionCurrent_019e03ad-7076-730b-8a6e-06c80cda5ccf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedEmployeeBenefitsCurrent_019e03ad-7076-790e-80a1-0641dc275029" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedEmployeeBenefitsCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7fd1-beaa-6e7bb4bc9b6a" xlink:to="loc_us-gaap_AccruedEmployeeBenefitsCurrent_019e03ad-7076-790e-80a1-0641dc275029" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_019e03ad-7076-78cd-b08f-efa816d8d337" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7fd1-beaa-6e7bb4bc9b6a" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_019e03ad-7076-78cd-b08f-efa816d8d337" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_019e03ad-7076-7a04-aed1-0511c74795c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7fd1-beaa-6e7bb4bc9b6a" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_019e03ad-7076-7a04-aed1-0511c74795c7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_019e03ad-7076-706e-bdd6-f7d3ef2f49a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7fd1-beaa-6e7bb4bc9b6a" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_019e03ad-7076-706e-bdd6-f7d3ef2f49a5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_019e03ad-7076-754f-b8c5-b1524424a3d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7fd1-beaa-6e7bb4bc9b6a" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_019e03ad-7076-754f-b8c5-b1524424a3d1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e03ad-7076-732e-af87-910b68dbad8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019e03ad-7076-79fb-befe-aa06b22431ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e03ad-7076-732e-af87-910b68dbad8e" xlink:to="loc_us-gaap_Liabilities_019e03ad-7076-79fb-befe-aa06b22431ff" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_019e03ad-7076-7d60-83e8-259979b003f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e03ad-7076-732e-af87-910b68dbad8e" xlink:to="loc_us-gaap_CommitmentsAndContingencies_019e03ad-7076-7d60-83e8-259979b003f2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e03ad-7076-739b-9162-e6e2799e848e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019e03ad-7076-732e-af87-910b68dbad8e" xlink:to="loc_us-gaap_StockholdersEquity_019e03ad-7076-739b-9162-e6e2799e848e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019e03ad-7076-7758-af7a-ba83032ea97c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7175-8af9-7d63c299caa3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e03ad-7076-7758-af7a-ba83032ea97c" xlink:to="loc_us-gaap_LiabilitiesCurrent_019e03ad-7076-7175-8af9-7d63c299caa3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019e03ad-7076-709d-ba4b-ca962a8f01e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e03ad-7076-7758-af7a-ba83032ea97c" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019e03ad-7076-709d-ba4b-ca962a8f01e6" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_019e03ad-7076-76ea-ba5c-5766e4d9606c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e03ad-7076-7758-af7a-ba83032ea97c" xlink:to="loc_us-gaap_FinanceLeaseLiabilityNoncurrent_019e03ad-7076-76ea-ba5c-5766e4d9606c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_019e03ad-7076-7c2e-8ef0-1061fbb731c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e03ad-7076-7758-af7a-ba83032ea97c" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_019e03ad-7076-7c2e-8ef0-1061fbb731c8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019e03ad-7076-7300-a661-541bb072ed5e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019e03ad-7076-7758-af7a-ba83032ea97c" xlink:to="loc_us-gaap_LongTermDebt_019e03ad-7076-7300-a661-541bb072ed5e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019e03ad-7076-7578-a8fc-3efc70e38626" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_019e03ad-7076-71be-85bc-6c6d28174d8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019e03ad-7076-7578-a8fc-3efc70e38626" xlink:to="loc_us-gaap_CommonStockValue_019e03ad-7076-71be-85bc-6c6d28174d8e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_019e03ad-7076-76d7-a6aa-0b9fd5cfe2a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019e03ad-7076-7578-a8fc-3efc70e38626" xlink:to="loc_us-gaap_AdditionalPaidInCapital_019e03ad-7076-76d7-a6aa-0b9fd5cfe2a9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e03ad-7076-7088-8001-943286ba6741" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019e03ad-7076-7578-a8fc-3efc70e38626" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019e03ad-7076-7088-8001-943286ba6741" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e03ad-7076-72c6-9267-226f942b480d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019e03ad-7076-7578-a8fc-3efc70e38626" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019e03ad-7076-72c6-9267-226f942b480d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019e03ad-7076-7753-acaf-b409fd7f80be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e03ad-7076-7e44-9e1f-f62fc2f32131" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019e03ad-7076-7753-acaf-b409fd7f80be" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019e03ad-7076-7e44-9e1f-f62fc2f32131" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019e03ad-7076-7ecd-8ba2-d3e97d706a83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019e03ad-7076-7753-acaf-b409fd7f80be" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019e03ad-7076-7ecd-8ba2-d3e97d706a83" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_019e03ad-7076-7103-ae6a-9aa8513cf088" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InventoryNet"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019e03ad-7076-7753-acaf-b409fd7f80be" xlink:to="loc_us-gaap_InventoryNet_019e03ad-7076-7103-ae6a-9aa8513cf088" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019e03ad-7076-7df9-9406-2e32a416e2f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsCurrent_019e03ad-7076-7753-acaf-b409fd7f80be" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019e03ad-7076-7df9-9406-2e32a416e2f7" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.billiontoone.com/role/StatementsofOperationsandComprehensiveIncomeLoss" xlink:type="simple" xlink:href="blln-20260630.xsd#StatementsofOperationsandComprehensiveIncomeLoss"/>
  <link:calculationLink xlink:role="http://www.billiontoone.com/role/StatementsofOperationsandComprehensiveIncomeLoss" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_019e03ad-7076-7229-95ea-54b27dc9deda" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpenses"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019e03ad-7076-7c40-b301-e779a3e3d439" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_019e03ad-7076-7229-95ea-54b27dc9deda" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019e03ad-7076-7c40-b301-e779a3e3d439" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019e03ad-7076-7350-a581-309469deeae7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingExpenses_019e03ad-7076-7229-95ea-54b27dc9deda" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019e03ad-7076-7350-a581-309469deeae7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e03ad-7076-7386-a6c8-40c79f11ef13" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019e03ad-7076-7490-a1be-6a94ca57148e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e03ad-7076-7386-a6c8-40c79f11ef13" xlink:to="loc_us-gaap_OperatingIncomeLoss_019e03ad-7076-7490-a1be-6a94ca57148e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019e03ad-7076-74cd-8d17-e5d92c8e6a91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e03ad-7076-7386-a6c8-40c79f11ef13" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_019e03ad-7076-74cd-8d17-e5d92c8e6a91" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019e03ad-7076-7130-bf6e-40a858ceba05" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_019e03ad-7076-75ef-a8a0-0b02a4a98cbf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossProfit"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_019e03ad-7076-7130-bf6e-40a858ceba05" xlink:to="loc_us-gaap_GrossProfit_019e03ad-7076-75ef-a8a0-0b02a4a98cbf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_019e03ad-7076-79af-bcbf-0bd5d9a462cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpenses"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OperatingIncomeLoss_019e03ad-7076-7130-bf6e-40a858ceba05" xlink:to="loc_us-gaap_OperatingExpenses_019e03ad-7076-79af-bcbf-0bd5d9a462cc" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e03ad-7076-724f-acff-3a4e1befa473" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e03ad-7076-761e-a78e-7958f2513bb1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019e03ad-7076-724f-acff-3a4e1befa473" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019e03ad-7076-761e-a78e-7958f2513bb1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019e03ad-7076-707b-8a65-16841e86744b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019e03ad-7076-724f-acff-3a4e1befa473" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019e03ad-7076-707b-8a65-16841e86744b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_019e03ad-7076-7333-bd1f-2b7c53812344" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e03ad-7076-7bb9-b9ed-3732f0bd2182" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_019e03ad-7076-7333-bd1f-2b7c53812344" xlink:to="loc_us-gaap_NetIncomeLoss_019e03ad-7076-7bb9-b9ed-3732f0bd2182" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_019e03ad-7076-7a5b-b850-210eddb72723" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossProfit"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e03ad-7076-77cb-aac4-17d85638191a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_019e03ad-7076-7a5b-b850-210eddb72723" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019e03ad-7076-77cb-aac4-17d85638191a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019e03ad-7076-7537-b80b-92f76780be3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_GrossProfit_019e03ad-7076-7a5b-b850-210eddb72723" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019e03ad-7076-7537-b80b-92f76780be3a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_019e03ad-7076-782b-a6cd-d74b814c04af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_019e03ad-7076-7e96-95f9-75227a6d9550" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_019e03ad-7076-782b-a6cd-d74b814c04af" xlink:to="loc_us-gaap_InvestmentIncomeInterest_019e03ad-7076-7e96-95f9-75227a6d9550" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019e03ad-7076-7383-b578-38b1831883b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_019e03ad-7076-782b-a6cd-d74b814c04af" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019e03ad-7076-7383-b578-38b1831883b7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_FairValueAdjustmentOfTermLoanIncludingInterest_019e03ad-7076-72ba-8707-1f1367ad63bb" xlink:href="blln-20260630.xsd#blln_FairValueAdjustmentOfTermLoanIncludingInterest"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_019e03ad-7076-782b-a6cd-d74b814c04af" xlink:to="loc_blln_FairValueAdjustmentOfTermLoanIncludingInterest_019e03ad-7076-72ba-8707-1f1367ad63bb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019e03ad-7076-7099-8061-5e7ab60c60c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NonoperatingIncomeExpense_019e03ad-7076-782b-a6cd-d74b814c04af" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019e03ad-7076-7099-8061-5e7ab60c60c9" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.billiontoone.com/role/StatementsofCashFlows" xlink:type="simple" xlink:href="blln-20260630.xsd#StatementsofCashFlows"/>
  <link:calculationLink xlink:role="http://www.billiontoone.com/role/StatementsofCashFlows" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e03ad-7076-7e48-af91-63df62ae1dde" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfDebt_019e03ad-713b-7b8c-a8d7-7d43251681a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e03ad-7076-7e48-af91-63df62ae1dde" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfDebt_019e03ad-713b-7b8c-a8d7-7d43251681a3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeasePrincipalPayments_019e03ad-713b-733a-b971-1f72bdcdabfa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeasePrincipalPayments"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e03ad-7076-7e48-af91-63df62ae1dde" xlink:to="loc_us-gaap_FinanceLeasePrincipalPayments_019e03ad-713b-733a-b971-1f72bdcdabfa" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentOfFinancingAndStockIssuanceCosts_019e03ad-713b-7fb2-8eab-a3e7af5899a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentOfFinancingAndStockIssuanceCosts"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e03ad-7076-7e48-af91-63df62ae1dde" xlink:to="loc_us-gaap_PaymentOfFinancingAndStockIssuanceCosts_019e03ad-713b-7fb2-8eab-a3e7af5899a1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_019e03ad-713b-795f-9397-af4a74fd2f22" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e03ad-7076-7e48-af91-63df62ae1dde" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_019e03ad-713b-795f-9397-af4a74fd2f22" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019e03ad-7076-7cf9-871c-2dfb411a226f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019e03ad-7076-7b14-a8f6-dcbdbba02767" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019e03ad-7076-7cf9-871c-2dfb411a226f" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019e03ad-7076-7b14-a8f6-dcbdbba02767" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019e03ad-713b-7bfd-9cc5-72df5d489ef9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_NetIncomeLoss_019e03ad-713b-7bfd-9cc5-72df5d489ef9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019e03ad-713b-75c7-91ea-f25838ae98eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_ShareBasedCompensation_019e03ad-713b-75c7-91ea-f25838ae98eb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortization_019e03ad-713b-7351-8e29-9f7a1058ec2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationAndAmortization"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_DepreciationAndAmortization_019e03ad-713b-7351-8e29-9f7a1058ec2e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense_019e03ad-713b-7da1-b3a0-aae7d74a74d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense_019e03ad-713b-7da1-b3a0-aae7d74a74d1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDispositionOfAssets1_019e03ad-713b-71b7-ab02-396b5aa91135" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnDispositionOfAssets1"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_GainLossOnDispositionOfAssets1_019e03ad-713b-71b7-ab02-396b5aa91135" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_FairValueAdjustmentOfCommonStockWarrantLiability_019e03ad-713b-748c-ae31-0e84b1ea24dd" xlink:href="blln-20260630.xsd#blln_FairValueAdjustmentOfCommonStockWarrantLiability"/>
    <link:calculationArc order="6" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_blln_FairValueAdjustmentOfCommonStockWarrantLiability_019e03ad-713b-748c-ae31-0e84b1ea24dd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_FairValueAdjustmentOfRedeemableConvertiblePreferredStockWarrantLiability_019e03ad-713b-7bf4-8ae8-42551ffb2bad" xlink:href="blln-20260630.xsd#blln_FairValueAdjustmentOfRedeemableConvertiblePreferredStockWarrantLiability"/>
    <link:calculationArc order="7" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_blln_FairValueAdjustmentOfRedeemableConvertiblePreferredStockWarrantLiability_019e03ad-713b-7bf4-8ae8-42551ffb2bad" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_FairValueAdjustmentOfTermLoan_019e03ad-713b-7e19-a5a4-fbaa12e79778" xlink:href="blln-20260630.xsd#blln_FairValueAdjustmentOfTermLoan"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_blln_FairValueAdjustmentOfTermLoan_019e03ad-713b-7e19-a5a4-fbaa12e79778" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_019e03ad-713b-7e41-9646-202634255925" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:calculationArc order="9" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_019e03ad-713b-7e41-9646-202634255925" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019e03ad-713b-75e8-972f-4cd141101443" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:calculationArc order="10" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019e03ad-713b-75e8-972f-4cd141101443" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_019e03ad-713b-74fd-b4aa-6ed36f3390f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_019e03ad-713b-74fd-b4aa-6ed36f3390f3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_019e03ad-713b-7f11-b4aa-ee2c2b1d3ea7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
    <link:calculationArc order="12" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_019e03ad-713b-7f11-b4aa-ee2c2b1d3ea7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities_019e03ad-713b-79fe-914d-0917a2fe46c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities_019e03ad-713b-79fe-914d-0917a2fe46c9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_019e03ad-713b-75af-a9b5-18db3f0c3e4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_019e03ad-713b-75af-a9b5-18db3f0c3e4e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities_019e03ad-713b-751f-939f-c587ab03a870" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities"/>
    <link:calculationArc order="15" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInEmployeeRelatedLiabilities_019e03ad-713b-751f-939f-c587ab03a870" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_019e03ad-713b-7729-ba90-6809e2b96871" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerLiability"/>
    <link:calculationArc order="16" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_019e03ad-713b-7729-ba90-6809e2b96871" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_019e03ad-713b-7a98-a898-8451584a172a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability"/>
    <link:calculationArc order="17" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_019e03ad-713b-7a98-a898-8451584a172a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_019e03ad-713b-7e51-870a-cd1894c16b8c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:calculationArc order="18" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-713b-723d-a28b-34e13d4e612d" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_019e03ad-713b-7e51-870a-cd1894c16b8c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019e03ad-7076-7c11-a7d8-f02715aff80a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-7076-74e2-8f44-493662eb6842" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019e03ad-7076-7c11-a7d8-f02715aff80a" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019e03ad-7076-74e2-8f44-493662eb6842" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019e03ad-7076-787e-9852-7089b44012e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019e03ad-7076-7c11-a7d8-f02715aff80a" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019e03ad-7076-787e-9852-7089b44012e0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e03ad-7076-7b7f-a44f-e4cbfe2bd798" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019e03ad-7076-7c11-a7d8-f02715aff80a" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019e03ad-7076-7b7f-a44f-e4cbfe2bd798" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.billiontoone.com/role/FairValueMeasurementsScheduleofFairValueMeasurementofAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="blln-20260630.xsd#FairValueMeasurementsScheduleofFairValueMeasurementofAssetsandLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://www.billiontoone.com/role/FairValueMeasurementsScheduleofFairValueMeasurementofAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_019e03ad-713b-76a6-a069-6ff2c7374df8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_WarrantsFairValueDisclosure_019e03ad-713b-784c-a23c-e955a238f98d" xlink:href="blln-20260630.xsd#blln_WarrantsFairValueDisclosure"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_019e03ad-713b-76a6-a069-6ff2c7374df8" xlink:to="loc_blln_WarrantsFairValueDisclosure_019e03ad-713b-784c-a23c-e955a238f98d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansPayableFairValueDisclosure_019e03ad-713b-7e80-bc67-0f81b9cc5d83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoansPayableFairValueDisclosure"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_019e03ad-713b-76a6-a069-6ff2c7374df8" xlink:to="loc_us-gaap_LoansPayableFairValueDisclosure_019e03ad-713b-7e80-bc67-0f81b9cc5d83" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019e03ad-713b-7aca-806c-e76bf800bd8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e03ad-713b-7d92-84e5-2c1206a8f76d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_019e03ad-713b-7aca-806c-e76bf800bd8f" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019e03ad-713b-7d92-84e5-2c1206a8f76d" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.billiontoone.com/role/AccruedExpensesandOtherCurrentLiabilitiesDetails" xlink:type="simple" xlink:href="blln-20260630.xsd#AccruedExpensesandOtherCurrentLiabilitiesDetails"/>
  <link:calculationLink xlink:role="http://www.billiontoone.com/role/AccruedExpensesandOtherCurrentLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedProfessionalFeesCurrent_019e03ad-713b-7b34-b7b1-674f360052ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedProfessionalFeesCurrent"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_us-gaap_AccruedProfessionalFeesCurrent_019e03ad-713b-7b34-b7b1-674f360052ff" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_AccruedInventoryPurchasesCurrent_019e03ad-713b-762e-9e70-cb7b4004f98a" xlink:href="blln-20260630.xsd#blln_AccruedInventoryPurchasesCurrent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_blln_AccruedInventoryPurchasesCurrent_019e03ad-713b-762e-9e70-cb7b4004f98a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_AccruedFixedAssetPurchasesCurrent_019e03ad-713b-7b5a-b11b-cbe882e31505" xlink:href="blln-20260630.xsd#blln_AccruedFixedAssetPurchasesCurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_blln_AccruedFixedAssetPurchasesCurrent_019e03ad-713b-7b5a-b11b-cbe882e31505" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxesPayableCurrent_019e03ad-713b-74e1-a381-b9bb5928ef76" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TaxesPayableCurrent"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_us-gaap_TaxesPayableCurrent_019e03ad-713b-74e1-a381-b9bb5928ef76" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_AccruedInformationTechnologyPurchasesCurrent_019e03ad-713b-7a2c-97d7-f595b1fc2b39" xlink:href="blln-20260630.xsd#blln_AccruedInformationTechnologyPurchasesCurrent"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_blln_AccruedInformationTechnologyPurchasesCurrent_019e03ad-713b-7a2c-97d7-f595b1fc2b39" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_AccruedLegalExpensesCurrent_019e03ad-713b-7934-9fbc-8b6a45a19b7c" xlink:href="blln-20260630.xsd#blln_AccruedLegalExpensesCurrent"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_blln_AccruedLegalExpensesCurrent_019e03ad-713b-7934-9fbc-8b6a45a19b7c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_AccruedPhlebotomyExpensesCurrent_019e03ad-713b-710c-84e1-c71d14090e71" xlink:href="blln-20260630.xsd#blln_AccruedPhlebotomyExpensesCurrent"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_blln_AccruedPhlebotomyExpensesCurrent_019e03ad-713b-710c-84e1-c71d14090e71" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedInsuranceCurrent_019e03ad-713b-7872-9dd9-3dde922d4ca9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedInsuranceCurrent"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_us-gaap_AccruedInsuranceCurrent_019e03ad-713b-7872-9dd9-3dde922d4ca9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedRentCurrent_019e03ad-713b-7264-8af7-9498242bb1e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedRentCurrent"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_us-gaap_AccruedRentCurrent_019e03ad-713b-7264-8af7-9498242bb1e8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_blln_AccruedClinicalExpensesCurrent_019e03ad-713b-71d9-8fc1-a3f650debb81" xlink:href="blln-20260630.xsd#blln_AccruedClinicalExpensesCurrent"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_blln_AccruedClinicalExpensesCurrent_019e03ad-713b-71d9-8fc1-a3f650debb81" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_019fb197-56b6-7579-a6e7-970a1156ed11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAccruedLiabilitiesCurrent"/>
    <link:calculationArc order="11" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019e03ad-713b-7d7f-9ace-4e2724c705b4" xlink:to="loc_us-gaap_OtherAccruedLiabilitiesCurrent_019fb197-56b6-7579-a6e7-970a1156ed11" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.billiontoone.com/role/NetIncomeLossPerShareScheduleofComputationofBasicandDilutiveNetLossPerShareDetails" xlink:type="simple" xlink:href="blln-20260630.xsd#NetIncomeLossPerShareScheduleofComputationofBasicandDilutiveNetLossPerShareDetails"/>
  <link:calculationLink xlink:role="http://www.billiontoone.com/role/NetIncomeLossPerShareScheduleofComputationofBasicandDilutiveNetLossPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e03ad-713b-7dbd-837a-27c1f56b12cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e03ad-713b-7440-898f-be9e8f8ea4f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e03ad-713b-7dbd-837a-27c1f56b12cd" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019e03ad-713b-7440-898f-be9e8f8ea4f8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019e03ad-713b-72ec-b293-ecd056ebd972" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e03ad-713b-7dbd-837a-27c1f56b12cd" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019e03ad-713b-72ec-b293-ecd056ebd972" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToCallOptionsAndWarrants_019e03ad-713b-7802-be80-b871e980ff6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToCallOptionsAndWarrants"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019e03ad-713b-7dbd-837a-27c1f56b12cd" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToCallOptionsAndWarrants_019e03ad-713b-7802-be80-b871e980ff6e" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
