Calculators that show their working
Search for the thing you need to work out. Every calculator here shows the formula it used and the steps it took, so the answer is something you can check rather than something you have to trust.
The formula is on the page, not behind it
Every calculator states the expression it evaluates and walks through how the answer is reached. That is the difference between a tool people come back to and a box that emits a number — and it answers the question sitting right beside the calculation, because people search for how to work something out at least as often as they search for something to work it out for them.
It runs in your browser
The arithmetic happens on your machine, so the result updates as you type and the page keeps working with our servers stopped. Nothing you enter is sent anywhere unless you sign in and choose to save it.
Every calculator is also a function
Each one is a verb on a shared adapter with its inputs and outputs declared, so the same calculation is available as an HTTP endpoint and as an MCP tool. The page and the endpoint run the same code and cannot drift apart.
Questions
Do I need an account?
No. Every calculator here is free, unlimited and works signed out. An account exists for keeping your work: saved calculations, a shareable link, and eventually a calculator you define yourself.
Does the maths run on your servers?
No. It runs in your browser, which is why the result appears as you type and why the page keeps working with our API stopped. The same functions are also available as an HTTP endpoint and an MCP tool if you want to call them from somewhere else.
Why do you show the formula?
Because a number with no working is something you have to trust rather than something you can check. Showing the formula and the steps also answers the question sitting next to the calculation — people search for how to calculate a thing at least as often as they search for a tool that does it.
Are the tax and finance calculators up to date?
They compute correctly from the rate you give them. They do not know your jurisdiction, and any calculator whose answer depends on a rate or a filing rule says so on its own page. A calculator that silently assumes one country’s rate is wrong for everyone else and looks identical either way.