Everyday maths should never feel like homework.

CalculatorWonder began with a simple frustration: the answers to ordinary questions — what a mortgage really costs, how much of a raise survives tax, how many days until a deadline — are buried under cluttered pages and jargon. We build the opposite. One question per page, one obvious answer, and a short explanation for anyone who wants to understand the working.

Today the library covers money and finance, health and fitness, maths and science, time and dates, unit conversions, business maths, household costs, vehicle and travel budgets, and study tools — with new calculators landing every month. Every tool is free, needs no account, and runs entirely in your browser.

Every calculator page shows the formula behind the answer and the assumptions it makes, so you can check the working instead of taking it on trust. Where a tool depends on rules that change — tax brackets, for example — the page says which year’s rules it uses.

Plain answers first

The number you came for sits at the top of every page, in large type, before any explanation or footnote.

Nothing hidden

Every tool states the formula and the assumptions it makes, so you can judge whether the result fits your situation.

Quick on any connection

Pages are lightweight, calculations run in your browser, and nothing you type is sent anywhere.

Built to grow

We start with the eight tools people ask for most and add more each month, guided by what visitors request.

Everything on CalculatorWonder is written and built by our own small team. Results are estimates intended for general guidance — for decisions with real consequences, check them with a qualified adviser. Tell us which calculator to build next.