All Calculator is a free collection of online calculators for percentages, fractions, math, money, health, dates and science. Every calculator shows its working, so you can see how an answer was reached instead of taking it on trust.
- Free to useNo sign-up, no downloads and no paywall.
- Working shownEach result comes with its formula and steps.
- Private by designCalculations run in your browser. We do not store your numbers.
- Checked by handEvery worked example is tested before a page goes live.
Why We Built All Calculator
Most online calculators give you a number and nothing else. That is fine until the answer looks wrong, or a teacher asks how you got it, or you need to explain a price to a customer. We wanted calculators that are fast to use but also show their working, explain the formula in plain English and point out the mistakes people commonly make.
So each calculator page has two parts: the tool itself, and a short guide underneath with the formula, worked examples and answers to common questions. You can use the result straight away, or learn the method and do it yourself next time.
Who Writes and Checks the Calculators
How We Build and Check Each Calculator
We start from a published formula
Math calculators use standard textbook methods. Health calculators use named sources, such as the World Health Organization’s BMI classification and the Mifflin-St Jeor equation, and each page lists them.
We work the examples by hand
Every worked example on a calculator page is calculated separately and must match the calculator’s answer before the page is published.
We test the awkward cases
Zero, negative numbers, very large values, leap years and inputs that make no sense are all tested, so the calculator gives a clear message instead of a wrong answer.
We show the working
Results include the formula and each step, so anyone can follow the method and check it.
We date every check
The “Last checked” date at the bottom of each page shows when it was last reviewed. Pages are checked again when a formula, rate or guideline changes.
What You Can Expect From Us
Your Numbers Stay With You
Calculations happen in your browser. We do not ask for an account and we do not store what you type. Our Privacy Policy explains the rest, including how cookies are used.
Plain English
Guides are written for people who want an answer, not a textbook. Terms are explained the first time they appear.
Free for Everyone
Every calculator and guide is free to use, with no sign-up, no paywall and no limit on how often you use them.
Errors Fixed
If you report a mistake, we check it. When we confirm and fix an error, we update the page and its “Last checked” date.
Our Calculator Categories
Health and Money Calculators
Health, finance and tax results are estimates for general information. They are not medical, financial or legal advice. Please speak to a qualified professional before making decisions based on them. Our Terms and Conditions explain this in full.
Found an Error or Want a New Calculator?
Every message is read by a person. Write to us at help@allcalculator.biz or use the contact form.