Common Questions

No. There is nothing to join and nothing to log into. Just pick a calculator and start typing.

No. Every calculator here is free to use, and you never have to pay for anything.

No. Whatever you type stays on your own device and disappears when you close the page. We never see it and we never save it.

The only things remembered are settings: whether you chose light or dark, and which grading scale you picked. Those are kept in your own browser, say nothing about you, and are never sent anywhere. Your marks, your salary and your bill are not among them.

There are no accounts, and nothing you type reaches a server — the sums happen inside your browser, so your numbers are never sent anywhere.

We do count visits, using Google Analytics. It sets two cookies and tells us which pages people opened and roughly where in the world they were. It cannot see what you typed into a calculator. We use it to work out which calculators are worth improving, and nothing else.

If you would rather not be counted, Google publishes an opt-out add-on for every browser, and Firefox, Safari, Brave and most ad blockers already block it. Nothing on this site behaves differently either way — the privacy policy explains all of it and lists the cookies by name.

Yes. It works on phones, tablets and computers, and the buttons are big enough to tap easily.

Nothing breaks. Just tap the box and type over it. The answer updates on its own, so you never have to press an "equals" button to try again.

Percent just means "out of a hundred". So 20% is 20 for every 100.

If a coat costs 100 and the sign says 20% off, you save 20. If the coat costs 50, you save 10 — half the coat, half the saving. The percentage stays the same, the amount changes with the price.

Open the percentage calculator. Type the percentage in the first box and the number in the second.

For example, 20 and 60 gives you 12, because 20% of 60 is 12.

Yes. Under every answer we write out exactly what we worked out in an ordinary sentence, so you can check it makes sense without doing the math yourself.

Open the tip calculator. Type in the bill, then tap 10, 15 or 20 percent, or type your own amount.

We show the tip on its own and the total to pay, so you have whichever number you need. How much to leave depends on the country — 15 to 20 percent is normal in the United States, while in much of Europe rounding up is plenty.

Open the discount calculator. Type in the normal price, then the number from the sale sign.

We show what you would actually pay and how much you save.

Open the bill split calculator. Type in the total and how many people are sharing it.

If you are tipping, add the percentage there too and it will be included in each share. The same calculator works for splitting rent, a taxi or a group present.