Percentage calculator
Work out X% of Y, what percent one number is of another, and percentage change.
How to use
Pick the kind of percentage question you have from the mode menu, then fill in the two values. The tool covers the everyday cases: finding X% of a number, working out what percentage one number is of another, calculating the percentage change between two numbers, and increasing or decreasing a value by a percentage.
Results update instantly as you type and can be copied with one click. Because the calculation runs in your browser, you can use it offline, and the Share button produces a link that reopens the calculator with the same mode and numbers filled in.
Percentages trip people up because the same word covers several different operations — this tool keeps them separate and labels each result with a plain-English sentence so you always know which question you answered.
Examples
What is 8.5% of 120? Choose “What is X% of Y”, enter 8.5 and 120, and read 10.2.
You scored 43 out of 50. Choose “X is what % of Y” to get 86%.
A price went from 80 to 100. “% change from X to Y” shows a 25% increase.
Frequently asked questions
How do I calculate percentage change?
Use the “% change from X to Y” mode. It computes (Y − X) / X × 100, so going from 200 to 250 is +25% and 200 to 150 is −25%.
What's the difference between “% of” and “is what %”?
“X% of Y” multiplies (e.g. 25% of 200 = 50). “X is what % of Y” divides (e.g. 50 is 25% of 200). They answer opposite questions.
Can I calculate a percentage increase or decrease?
Yes. Use the Increase or Decrease mode to add or subtract a percentage of a base value — handy for markups, discounts and raises.
Is my data private?
Completely. Everything is calculated locally in your browser; no numbers are uploaded.
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