Calculators that show their working

How it works

No black boxes. Every calculator walks you through the method so you can check the answer and learn how it’s done.

1. 1

   Pick a calculator

   Search by name or browse by subject — arithmetic, geometry, finance, conversion, and more.

2. 2

   Enter your numbers

   Fillable, clearly-labelled inputs. No sign-up, no paywall, nothing to install.

3. 3

   See the working

   Get the answer plus the formula, the substitution, and every step that leads to it.

Frequently asked questions

Are these calculators free?

Yes — every calculator on calculatethis.io is completely free to use, with no sign-up, account, or paywall.

Do you store the numbers I enter?

No. Calculations run in your browser. The values you type are not sent to a server or saved.

What makes these different from other calculators?

Each one shows its working — the formula, the substitution, the arithmetic, and the result — so you can learn the method and verify the answer, not just copy a number.

How accurate are the results?

Results use standard mathematical formulas and full-precision arithmetic, then round only for display. For most everyday and academic use they are exact.

Can I use these on my phone?

Yes. Every page is responsive and works on phones, tablets, and desktops with no app to install.