Editorial policy

How we make sure our calculators are accurate, transparent and up to date.

1. Sources

Country rules (tax brackets, social insurance, minimum wage, benefits) come from the official government source for that country and year.
Scientific, medical and engineering formulas come from standards bodies (ISO, IEC, WHO, NIST, IUPAC…), official guidelines or peer-reviewed papers.
The source and formula are shown on each calculator page. Where a widely used community formula is used (for example in sports or gaming), we say so.

2. Accuracy checks

Before publishing, every calculator is run automatically in a real browser on desktop and phone sizes to catch errors, impossible results (NaN, ∞) and layout problems.
Default examples are compared with a hand calculation, an official worked example, or a reference implementation.
Numbers are calculated with double-precision arithmetic; special functions are accurate to at least 7 significant digits.

3. Updates and review dates

Country rules are reviewed at least once a year and whenever the law changes. Each page shows a “last reviewed” month. If a rule changes before we update a page, the page may be out of date — please tell us.

4. Health, money and safety topics

Health calculators show a clear “not a diagnosis” note; we do not publish medication-dosing calculators.
Money and tax tools give estimates, not advice.
Engineering tools are for learning and estimates; real designs must follow local codes and be checked by a qualified engineer.
We do not publish tools that mainly help attack systems or people.

5. Independence and advertising

The site is free and supported by advertising. Advertisers have no influence on results or content. Embedded widgets carry no ads.

6. Privacy

Calculations run in your browser. We use anonymous analytics to see which tools are used; see our privacy policy.

7. Corrections

Report errors through the report-an-error form. Confirmed errors are fixed and the review date is updated.

Policy last updated: November 2026.