Our methodology
Reviewed by the CalcCafe editorial team · Last updated 1 July 2026
How every CalcCafe calculator is researched, built, checked against a primary source, and kept up to date. This is the standard we hold all 500+ tools to.
1. We start from a primary source, not a competitor
Before a calculator is written, we identify the authoritative definition of the formula it implements. For U.S. tax tools that is the Internal Revenue Service and the underlying statute; for body-composition tools it is the World Health Organization and peer-reviewed equations such as Mifflin-St Jeor; for unit conversions it is the International System of Units as maintained by the BIPM and NIST. We never reverse-engineer a number from another calculator site, because that propagates errors and cannot be audited.
2. We publish the formula and a worked example
Each tool page states the exact formula it uses and shows at least one fully worked example with real numbers, so you can reproduce the result by hand. If the maths on the page and the maths in the example ever disagree, that is a bug we want reported.
3. Everything runs in your browser
Calculations execute entirely on your device in JavaScript. Nothing you type — salaries, loan balances, health metrics, files — is transmitted to or stored on a server. This is a deliberate privacy choice and it also means results are instant and work offline once the page has loaded.
4. Year-specific rules are dated and versioned
Tax brackets, contribution limits and similar figures change annually. Where a tool depends on a specific year's rules, we label the year in the interface and verify the values against the current official tables. Every tool carries a visible "last updated" date.
5. YMYL tools get extra review
Tools that touch money, health or legal decisions (“Your Money or Your Life” topics) are reviewed a second time for accuracy and for clear, non-advisory language before they are published or revised. CalcCafe provides educational estimates, never professional advice.
6. Corrections are prioritised
If you find a discrepancy, email [email protected] with the tool name and the inputs you used. Verified calculation errors are fixed ahead of everything else and the tool's update date is revised.
Sources we rely on
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