Percentage calculator
X% of Y, X is what % of Y, and percentage change.
This runs in your browser. Nothing is uploaded.
About Percentage calculator
Calculates X percent of Y, what percent X is of Y, and percentage change, in your browser, with no form submission.
Three questions eat most percentage searches: what is X% of Y, what percent is X of Y, and how much did a number change. Putting them on one page means I do not maintain three nearly identical forms, and you do not have to guess which landing page matches the sentence in your head.
The first block is X% of Y, defaulting to 10% of 200 so you can see a result before you overwrite it. The second is 'X is what percent of Y'. The third is percentage change from A to B, which is (B − A) / A, and which is undefined if A is zero — the page will not invent a number. All three update as you type. None of them are sent anywhere.
I did not add a tip calculator or a 'markup vs margin' explainer. Those are different jobs with different footguns. If you need a tip split, use a spreadsheet or do the first block twice. If you need units, use the unit converter. Percentages here are ordinary real-number arithmetic.
How to use Percentage calculator
- 1Use the first block for X% of Y.
- 2Use the second for 'X is what percent of Y'.
- 3Use the third for percentage change from one value to another.
What it won't do
- No compound interest, no tax tables, no tip split.
- Division by zero is refused, not pretty-printed as Infinity.
Common questions
What formula does 'percentage change' use?
(to − from) / from, times 100. An increase from 10 to 200 is +1900%. A drop from 200 to 10 is −95%. If 'from' is zero, there is no finite percentage change and the result stays blank-looking rather than Infinity.
Is 'X% of Y' the same as 'X is what % of Y'?
No. 10% of 200 is 20. 10 as a percent of 200 is 5%. The two blocks sit on the same page because people mix the sentences up, not because the math is the same.
Why is there no tip calculator on this percentage page?
A tip tool is a bill split dressed as math, and it does not belong next to image and text tools. Use X% of Y for the tip amount if you want the arithmetic without the theatre.
Related tools
Why this one doesn't upload your file
There is no server to upload to. This page is a static file, and the work happens in your browser using the same graphics and WebAssembly code that renders every other site you visit. Your file is read from disk into memory, processed, and handed back as a download. Once the page has loaded you can disconnect from the network entirely and it keeps working. The longer explanation