Type a percentage and a value to see the result, with the sentence spelled out so you can check you asked the right question.
Result
Everything is worked out in your browser. Nothing is sent anywhere.
A percentage is a fraction with 100 on the bottom. "15%" means fifteen hundredths, so 15% of 200 is 200 × 15 ÷ 100 = 30. That is the whole rule, and every other percentage question is a rearrangement of it.
A shortcut worth knowing: the two numbers can swap places. 15% of 200 and 200% of 15 are both 30, because multiplication does not care about order. That turns awkward sums into easy ones — 4% of 75 looks like work, but 75% of 4 is three, in your head.
Percentages above 100 are perfectly ordinary and a surprising number of calculators refuse them. 250% of 40 is 100. If a tool caps you at 100%, it has confused "percentage" with "proportion of a whole".
Divide the percentage by 100, then multiply by the value. For 15% of 200: 15 ÷ 100 = 0.15, and 0.15 × 200 = 30. Moving the decimal point two places left is the same as dividing by 100, which is why 10% of anything is just that number with the point moved once.
Yes. 100% is the whole thing, so 250% is two and a half times it. A price that triples has risen 200% — the increase is 200%, and the new price is 300% of the old one. Those two sentences describe the same change and the numbers differ, which is why the wording matters.
No. The calculation runs in your browser with a few lines of JavaScript. There is no server to send it to — this site is static files.
Add, subtract, multiply and divide fractions — exactly, never rounded.
Solve a proportion — with the inverse case the usual formula gets wrong.
Add a percentage to a value, or find the increase between two numbers.
The price after a discount — and the price before it, from the sale tag.
The tip, the total and what each person owes — including the cent that does not divide.
How far apart two values are, with neither one as the reference.