How We Calculate

Each calculator is powered by a small, pure calculation engine that is unit-tested against known results. Investment growth uses standard compound-interest math; loans and mortgages use the standard amortization formula; income tax applies the federal progressive brackets; payroll uses Social Security and Medicare (FICA) rules.

Dated, sourced data

Tax brackets, the standard deduction, FICA parameters, and contribution limits are tied to a specific tax year and stored in a single source of truth. We never duplicate these figures across the codebase. See the data sources page for the official references and review status.

Limitations

Calculators provide estimates. Tax tools currently cover federal rules only and do not include state taxes. Results are educational and do not replace professional advice.