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Finance & LoansGenerated accuracy model review: 2026-05-06
Loan 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
- This calculator uses the standard amortization formula found in most financial textbooks. It assumes a fixed interest rate and equal monthly payments over the life of the loan. The mathematical formula is: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Loan Amount: $25,000
- Annual Interest Rate: 5.5%
- Loan Term: 5 Years
Expected outputs
- Estimated Monthly Payment: $477.53
- Total Interest Paid: $3,651.74
- Total Loan Cost: $28,651.74
Known limitations
- This calculator assumes a fixed interest rate for the entire duration of the loan. It does not account for variable rates, prepayment penalties, or late fees.
Assumptions
- Inputs are interpreted exactly as entered in the calculator form.
- The calculation runs locally in the browser using the current checked-in calculator definition.
Unit handling
- Loan Amount accepts values in $.
- Annual Interest Rate accepts values in %.
- Loan Term accepts values in Years.
- Estimated Monthly Payment is displayed as currency.
- Total Interest Paid is displayed as currency.
- Total Loan 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 loan-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Loan Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.