About Numbarn
Numbarn currently offers 240 fully reviewed calculators (240 available in total) you can use without creating an account. Everything runs in your browser: your inputs stay on your device unless you choose to share a link.
We combine serious tools (mortgage, BMI, percentages, loans) with lighter ones (space distances, pizza splits) so you can get a quick answer and move on with your day.
Site operator
Ahmet Ozdemir is the founder and independent developer of Numbarn. The project started to provide transparent, private calculators with visible formulas and references rather than opaque widget pages.
Builds and maintains Numbarn calculator products, formula implementations, and quality review workflows.
How we ensure accuracy
Every calculator formula is tested against known reference values before publishing. Financial calculators (tax, mortgage, retirement, loan) are reviewed when tax codes or rates change — typically at the start of each tax year. Health calculators use formulas from published medical and nutrition research, cited on each calculator page.
See How We Test for the full validation workflow and Corrections for public change logs.
Privacy by design
Calculator inputs are processed entirely in your browser. We do not store your inputs on our servers, require a login, or track individual calculations. Favorites and recent tools are saved in your browser's localStorage and never transmitted. See our Privacy Policy for full details.
Not professional advice
Financial and health results are educational estimates only. Tax laws, lender rules, and health guidelines vary by jurisdiction and individual situation. Always verify with a qualified professional before making financial, medical, or legal decisions. See our Terms for limitations.
How we make money
Numbarn is free to use. We may display advertisements through Google AdSense and include clearly labeled affiliate links on some pages (e.g. mortgage rate comparisons). These help keep the site running. Affiliate partnerships never influence calculator results.
Found an error?
If you believe a calculator is producing incorrect results, please contact us with the calculator name, inputs you used, the result you got, and the result you expected. We investigate every report and update formulas promptly.
Review ownership by topic
- Finance pages: formula review against IRS/CFPB/SEC references and annual updates.
- Health pages: source review against CDC/WHO/NIH or comparable references.
- Education/math pages: formula checks against standard academic references.
- General utilities: usability, edge-case handling, and correctness checks.