Methodology & Sources

This page lists how every calculator on SumFrog works and where its data comes from. It is updated whenever a formula or data source changes.

Principles

Every calculator page displays its formula in mathematical notation with at least one worked example. Rates and reference values (tax rates, thresholds, medical constants) always link to the official source — IRS, SSA, BLS, CDC, state tax authorities — with a "Last updated" date. Estimates are labeled as estimates. We do not publish numbers we cannot verify against a primary source.

Formula registry

The full formula and source list for each tool appears on the tool's own page under "How it works" and "Data & sources". This registry is regenerated automatically at every site build.

Disclaimers

Tools are informational only — not financial, tax, legal, or medical advice. Consult a qualified professional for decisions.