Percentage calculator
Three everyday percentage questions, answered as you type.
How to calculate percentages
A percentage is a fraction out of 100. This calculator answers the three questions that come up most often, each in its own tab, so you do not have to remember which formula to use.
The three formulas
X is what % of Y = (X ÷ Y) × 100
change from A to B = ((B − A) ÷ A) × 100
Worked examples
- 15% of 200 = 0.15 × 200 = 30
- 30 is 25% of 120
- From 80 to 100 is a +25% increase
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. For example, 20% of 50 is 0.20 × 50 = 10. Use the first tab above.
How do I find what percentage one number is of another?
Divide the first number by the second and multiply by 100. So 30 out of 120 is (30 ÷ 120) × 100 = 25%. Use the second tab.
How do I calculate a percentage increase or decrease?
Subtract the old value from the new value, divide by the old value, and multiply by 100. A rise from 80 to 100 is a 25% increase. Use the third tab.
How do I add a percentage to a number?
Work out the percentage of the number, then add it on. To add 15% to 200, calculate 15% of 200 (30) and add it for 230.
What is percentage difference?
Percentage change compares a new value to an original one. Percentage difference compares two values relative to their average and is always positive; for most everyday needs, percentage change is what you want.