About Numerith

Numerith — “Smart Calculators. Clear Answers.” — is a free collection of 360 calculators and converters across 12 categories, from mortgages and payroll to health, dates, units, science and networking.

What we believe

• Correct first. Every calculator implements an established formula, documents it, and is tested against independently computed reference values — 1237 calculator test cases in total. The site cannot be built if any of them fail.
• Transparent. Each page shows the formula, assumptions, limitations, a worked example generated by the tool itself, and whether the result is exact or an estimate.
• Private. Calculations happen in your browser. Your inputs are never sent to us. There are no accounts, paywalls or email capture.
• Honest. We do not show invented ratings, user counts or testimonials, and we do not assume your currency, tax rules or health standards.

How content is produced

Calculator explanations were drafted with the help of AI tools and are verified against the implemented formulas by automated tests. Each page shows whether a person has completed an editorial review; pages that have not are clearly marked. Corrections are welcome via the contact page.

Funding

Numerith is free to use. It may in future be supported by clearly labelled advertising, which will never be placed inside calculators or results and never receives your inputs.