Calculation Standards and Review Process

Every input uses the unit shown next to it, and the result comes back in that same unit. Currency is displayed with the symbol or suffix the locale expects.

The calculators never fetch exchange rates. Convert first with the currency converter if your figures are in another currency.

Formulas follow textbook and standards-body definitions and are printed in plain text on each calculator page, so they can be quoted or checked by hand.

Rounding is applied only when a value is displayed. Intermediate values are not rounded, so recomputing from the numbers on screen can differ by a small amount.

Sales tax, savings-income tax and lottery tax differ by country. Rates and brackets are kept in per-locale rule files, and the official authority is linked under each calculator.

Rates change with legislation. Always confirm the current official guidance before filing a return or signing a contract.

They use only the values you enter: no live exchange rates, no investment advice and no tax consultation.

Health calculators apply general reference values and do not replace a personal diagnosis.

A report goes through: reproduce → fix the code → pass the verification scripts → update the page’s last-modified date.

Every build runs known-answer checks, indexing/structured-data checks and translation completeness checks to catch regressions.