Percentage Calculator: Percent Of, Percent Change
Three common percentage questions answered live.
What is X% of Y?
X is what % of Y?
Percent change
How to use it
- Use the first box for questions like "what is 15% of 80?".
- Use the second box for "18 is what percent of 72?".
- Use the third box to find the percent increase or decrease from one value to another.
How it works
Percent means "per hundred". To find a percent of a number, multiply by the percent and divide by 100: 15% of 80 = 15 × 80 ÷ 100 = 12.
Percent change is (new − old) ÷ old × 100. Going from 50 to 65 is a 30% increase. Going from 80 to 60 is a 25% decrease.
Questions
Why is a 25% decrease not undone by a 25% increase?
The second percentage is taken from a smaller number. 80 down 25% is 60, and 60 up 25% is only 75.
Can I use decimals?
Yes, for example 7.5% of 40 works.