How to calculate percentages
Percent of a number
To find X% of Y, multiply Y by X and divide by 100: Y × X ÷ 100. Example: 20% of 150 = 150 × 20 ÷ 100 = 30.
What percent one number is of another
To find what percent X is of Y, divide X by Y and multiply by 100: X ÷ Y × 100. Example: 30 of 150 = 30 ÷ 150 × 100 = 20%.
Percentage change
To find the change from an old value to a new value, subtract old from new, divide by the old value, and multiply by 100: (new − old) ÷ old × 100. A positive result is an increase, a negative result a decrease. Example: 80 → 100 is (100 − 80) ÷ 80 × 100 = +25%.
Related calculators
Working with money over time? See the compound interest calculator or the loan payoff calculator.
Frequently asked questions
- How do I calculate what is X percent of a number?
- Multiply the number by the percent and divide by 100 (e.g. 20% of 150 = 30).
- How do I find what percent one number is of another?
- Divide the first by the second and multiply by 100 (e.g. 30 of 150 = 20%).
- How do I calculate a percentage increase or decrease?
- (new − old) ÷ old × 100. Positive is an increase, negative is a decrease.