Formulas in the open
Every calculator page explains the formula it uses and the assumptions behind it, so you can check the working — not just trust a number. Read the methodology.
The right calculator, one search away.
648 free tools across finance, health, math, construction and more. Each one shows its working, runs in your browser, and never asks for an account.
648 calculators
16 categories
0 sign-ups
formulas shown on every page
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Runs in your browser
Tools load as plain pages and calculate locally. There is nothing to install, no account to create, and your inputs are not sent to a server.
Honest about limits
These are reference estimates, not professional advice. Where a topic touches health, tax, or money, the page says so plainly — see the disclaimer.
Common questions
Are the calculators free to use?
Yes. Every calculator on this site is free, with no account, subscription, or download required.
How accurate are the results?
Each tool uses standard, published formulas and states its assumptions on the page. Results are reliable estimates for planning — for medical, legal, or financial decisions, confirm with a qualified professional.
Do you store what I type into a calculator?
No. Calculations run in your browser, so your inputs are not sent to our server. We only use basic analytics to count page visits.
Can I request a calculator or report a mistake?
Yes — use the contact page. Corrections and new tool requests are the main way this catalog improves.