We build the calculator library we always wanted.
A single trustworthy place for quantitative questions — one that explains the number as well as computes it.
What Numora is
Numora is a free library of over 4,000 online calculators, covering math, finance, health, physics, chemistry, engineering, construction, automotive, computing, statistics, and everyday life. Every calculator is a focused, embeddable tool with a reviewed formula, live interpretation, and worked examples. The entire site is available without sign-up, without ads in the calculation flow, and without sending your inputs to any server — the math runs locally in your browser.
Editorial standard
We maintain one editorial standard across the whole library, inspired in equal parts by Wikipedia's citation discipline and good academic writing:
- Formulas are sourced. Every calculator links to a primary source — CFPB, WHO, IRS, IUPAC, Freddie Mac, depending on the domain. The citation is visible on the page.
- YMYL calculators are reviewed. Finance, health, and legal tools carry a reviewer byline. The reviewer's name and credential appear on every page they've signed off on.
- Assumptions are disclosed. Whatever the engine assumes about year conventions, rounding, bracket schedules, or unit conventions is printed at the bottom of every calculator. No black boxes.
- Interpretation is plain English. We explain what the number means for your specific inputs, in one sentence, as you type. Raw numbers without context are where most calculator sites fail.
Privacy posture
All calculation happens in your browser. Inputs are not sent to our servers, not logged, and not stored. We use aggregate analytics to understand which calculators are useful and how pages are performing — nothing that could identify an individual user.
How to reach us
Found a bug, a broken formula, or a calculator we should add? Email hello@numora.net, or visit our contact page. We read every message.