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Finance & LoansGenerated accuracy model review: 2026-05-06
Student 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
- Standard: P*r*(1+r)^n / ((1+r)^n - 1). Accelerated: Iterative principal reduction.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Loan Balance: $30,000
- Interest Rate: 5.8%
- Loan Term: 10 Years
- Extra Monthly Payment: $0
Expected outputs
- Standard Payment: $330.06
- New Payoff Time: 10 Years
- Interest Saved: $0.00
- Total Interest (Standard): $9,606.77
Known limitations
- This calculator assumes a fixed interest rate. It does not account for income-driven repayment (IDR) adjustments, forgiveness programs (PSLF), or variable rate fluctuations.
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 Balance accepts values in $.
- Interest Rate accepts values in %.
- Loan Term accepts values in Years.
- Extra Monthly Payment accepts values in $.
- Standard Payment is displayed as currency.
- Interest Saved is displayed as currency.
- Total Interest (Standard) 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 student-loan-repayment-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Student Loan Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.