Methodology

This page explains how BudgetFolk decides what goes into a calculator and how we keep the math honest once it's live.

Sourcing

Every calculator's "How this is calculated" section names the formula or method it uses, and the "Sources" section (where the underlying research allows for direct citation) links to or names the primary source. If a number on this site isn't backed by a cited source, that's a bug — tell us at the email on the Contact page.

Verification

Calculator logic is written as plain, testable functions, and each one is checked against known-good reference values calculated by hand from the cited source before it ships. That separates the math from the page design — a visual change to a calculator can't silently change its numbers, because the underlying calculation is tested independently of how it's displayed.

Keeping it current

Every calculator page shows a "Last updated" date. When a formula, source or constant changes, that date changes with it. If you spot something that looks outdated or wrong, that's exactly what the Contact page is for.