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Finance & LoansGenerated accuracy model review: 2026-05-06
Compound Interest 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
- Formula: **A = P(1 + r/n)^(nt)** * **P**: Principal * **r**: Annual Rate (decimal) * **n**: Times compounded per year * **t**: Years The more frequent the compounding, the higher the return.
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Principal Amount: $5,000
- Annual Interest Rate: 7%
- Time Period: 10 Years
- Compounding: Monthly (12/yr)
Expected outputs
- Future Value: $10,048.31
- Total Interest Earned: $5,048.31
Known limitations
- This version calculates a lump sum growth. For regular monthly contributions, use the Investment Calculator.
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
- Principal Amount accepts values in $.
- Annual Interest Rate accepts values in %.
- Time Period accepts values in Years.
- Compounding accepts one of the configured options.
- Future Value is displayed as currency.
- Total Interest Earned 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.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current compound-interest-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Compound Interest.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.