General tool / 05
Percentage Calculator
Calculate a percentage of a value, a ratio as a percent, or percentage change.
Percentage Calculator: Three calculations in one place. X% of Y multiplies Y by X ÷ 100, so 15% of 240 is 36. X is what % of Y divides X by Y and multiplies by 100, so 30 is 25% of 120. Percentage change from X to Y divides the difference by the starting value, so a price going from 80 to 100 is a 25% increase, and from 100 to 80 a 20% decrease. Runs 100% locally in your browser with zero server file uploads.
- Category
- Everyday tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
Working back to the original
A common slip is removing a percentage from a total that already includes it. A price of 120 including 20% tax was 100 before tax, not 96: the tax was 20% of the original, so divide by 1.2 instead of subtracting 20%. The same applies to a sale price after a 25% discount, which is 75% of the original, so divide it by 0.75. The reverse percentage calculator does this step when you enter the total as the result and 120 or 75 as the percentage.
Change, difference, and margin
Percentage change needs a starting point. When two values are simply compared, such as two shops' prices, neither is the base, and the percentage difference divides by their average instead, so 80 and 100 differ by about 22% whichever comes first.
Markup and margin are the classic mix-up in pricing. Buying at 60 and selling at 100 is a 66.7% markup on cost but a 40% margin on the selling price; the profit margin calculator shows both.
How to use it
- Choose a calculation: X% of Y, X is what % of Y, or % change from X to Y.
- Enter both values.
- Calculate and copy the result.
Privacy & limitations
Values remain local. Results use browser number precision and should be independently checked for financial decisions.
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Frequently asked questions
Does this upload my input?
No. The work happens in your current browser tab.
How is percentage change calculated?
Subtract the old value from the new one, divide by the old value, and multiply by 100: (new − old) ÷ old × 100. From 50 to 65 is (65 − 50) ÷ 50 × 100 = 30%. A negative result is a decrease.
How do I work out a percentage of a number?
Divide the percentage by 100 and multiply by the number. 20% of 350 is 0.20 × 350 = 70. Moving the decimal point two places is the same thing: 7% is 0.07.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. 18 out of 24 is 18 ÷ 24 × 100 = 75%.
Why isn't a 20% rise followed by a 20% fall back to where it started?
Each percentage applies to a different base. 100 up 20% is 120; 120 down 20% is 96, because the fall is 20% of 120, not of 100.
What is the difference between percentage change and percentage points?
Percentage points compare two percentages directly: a rate moving from 4% to 5% rose by 1 percentage point, which is a 25% increase in the rate itself.
Free tool · runs in your browser · no account required