Tools / Percentage Calculator
Percentage Calculator
Three quick calculators in one: percent of a number, one number as a percent of another, and percentage change.
What is X% of Y?
X is what percent of Y?
Percentage change from X to Y
The three formulas
Percent of a number: multiply the number by the percentage and divide by 100. For example, 15% of 2,400 is 2,400 × 15 / 100 = 360.
One number as a percent of another: divide the part by the whole and multiply by 100. For example, 30 out of 120 is 30 / 120 × 100 = 25%.
Percentage change: subtract the old value from the new value, divide by the old value and multiply by 100. Going from 80 to 100 is (100 − 80) / 80 × 100 = 25% increase. A negative result is a decrease.
Everyday uses
Use it to work out a discount in a shop, the tip on a restaurant bill, a salary raise, exam marks or the growth of an investment. A common mistake is reversing the base: a 20% discount followed by a 20% increase does not return you to the original price, because the second percentage is applied to a smaller number.
Frequently asked questions
Why is percentage change not symmetrical?
Because the base changes. A rise from 100 to 150 is +50%, but a fall from 150 to 100 is about -33.3%.
Can I enter decimals?
Yes. All fields accept decimal values.
What if the starting value is zero?
Percentage change from zero is undefined, so the tool shows a dash.