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Real Estate InvestorGenerated accuracy model review: 2026-05-06

BRRRR Calculator accuracy and testing

This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.

Formula source

  • All-in cost = purchase price + rehab budget + closing costs + reserves. Refinance loan proceeds = ARV x refinance LTV / 100. Cash left in deal = all-in cost - refinance loan proceeds. Monthly NOI = monthly rent - monthly operating expenses. Monthly cash flow after refinance = monthly NOI - refinance monthly debt service. DSCR = monthly NOI / refinance monthly debt service.

Test cases

Default input regression check

Generated from the checked-in default inputs and calculate function.

Inputs

  • Purchase Price: $190,000
  • Rehab Budget: $55,000
  • Closing Costs: $8,000
  • Reserves: $7,000
  • After-Repair Value: $330,000
  • Refinance LTV: 75%
  • Monthly Rent: $2,600
  • Monthly Operating Expenses: $900
  • Refi Monthly Debt Service: $1,250

Expected outputs

  • Cash Left in Deal: $12,500.00
  • Refinance Loan Proceeds: $247,500.00
  • Monthly Cash Flow After Refi: $450.00
  • DSCR: 1.36
  • All-In Cost: $260,000.00

Known limitations

  • This calculator is a planning model only. It does not predict appreciation, market liquidity, lender approval, tax treatment, insurance availability, permit risk, legal obligations, construction defects, tenant behavior, or final sale price.

Assumptions

  • All costs, rents, ARV, loans, reserves, fees, and rates are user-entered assumptions.
  • Calculations are deterministic and do not fetch market rents, tax rules, insurance quotes, lender terms, or property records.
  • Results are estimates only and are not financial, tax, legal, lending, appraisal, inspection, or investment advice.

Unit handling

  • Purchase Price accepts values in $.
  • Rehab Budget accepts values in $.
  • Closing Costs accepts values in $.
  • Reserves accepts values in $.
  • After-Repair Value accepts values in $.
  • Refinance LTV accepts values in %.
  • Monthly Rent accepts values in $.
  • Monthly Operating Expenses accepts values in $.
  • Refi Monthly Debt Service accepts values in $.
  • Cash Left in Deal is displayed as currency.
  • Refinance Loan Proceeds is displayed as currency.
  • Monthly Cash Flow After Refi is displayed as currency.
  • All-In Cost is displayed as currency.

Rounding rules

  • Number displays use up to 2 decimal places in the calculator UI.
  • Currency outputs are displayed with standard US dollar formatting.
  • Input precision follows configured step values where provided.

Version history

1.0.0 - 2026-05-06

Generated accuracy and testing page from the current brrrr-calculator calculator definition.

Change log

2026-05-06

Published default regression test documentation and metadata fallbacks for BRRRR Calculator.

Calculator transparency

Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.

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