Percentage Calculator
Three everyday questions in one place: what is X% of Y, X is what percent of Y, and how much has a value changed in percent.
Your details
What is X% of Y?
X is what percent of Y?
Percentage change
Result
20% of 150
30
- 12 is what % of 80
- 15.00%
- 50 → 75
- +50.00% increase
- % of: value × percentage ÷ 100. Percent of: part ÷ whole × 100. Change: (new − old) ÷ |old| × 100.
Good to know: 20% of 150 is 30. Divide the percentage by 100, then multiply.
About this tool
Three everyday percentage calculations: a percentage of a number, what percent one number is of another, and the percentage change between two values.
Formula
% of X: value × percentage ÷ 100. What percent: part ÷ whole × 100. Change: (new − old) ÷ |old| × 100.
Reference values
- 15% of 80 = 12
- 12 of 80 = 15%
- Percentage change uses the old value as the base
Questions people ask
How do I calculate a percentage of a number?
Multiply the number by the percentage, then divide by 100. For 15% of 80: 80 × 15 ÷ 100 = 12.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. 12 of 80 is 15%.
Why doesn't a 50% loss get undone by a 50% gain?
The gain applies to a smaller amount. Lose 50% of 100 and you have 50. Gain 50% of 50 and you have 75, not 100.
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How we calculate this
We use the standard published formula or definition for this calculation, and we show the working so you can check it.
Spotted a mistake? Tell us and we'll check it. How we check our calculators