Percentage Calculator
Solve the three everyday percentage questions: a percentage of a number, what percent one number is of another, and the percentage change between two values. Each answer is shown step by step.
About the Percentage Calculator
A percentage is a number expressed as a part of 100. 25% means 25 out of every 100, or one quarter.
Percentages turn up everywhere: discounts and tax, exam marks, interest rates, nutrition labels, and changes in prices or salaries.
The formula
X% of Y = X ÷ 100 × Y
- What percent
- part ÷ whole × 100
- Percentage change
- (new − old) ÷ |old| × 100
How to read your result
- A positive change is an increase; a negative one is a decrease.
- Percentage changes are not symmetric: going up 25% then down 25% does not bring you back to the start.
- Percentage points are different from percent. A rate going from 4% to 5% rises 1 percentage point, which is a 25% increase.
Worked example
A shirt priced 1,200 with 15% off
- 15 ÷ 100 = 0.15
- 0.15 × 1,200 = 180 off
- You pay 1,200 − 180 = 1,020
Questions people ask
How do I add a percentage to a number?
Multiply by 1 plus the percentage as a decimal. To add 18% tax to 500: 500 × 1.18 = 590.
How do I reverse a percentage?
Divide by 1 plus the percentage. If 590 includes 18% tax, the price before tax is 590 ÷ 1.18 = 500.
What is percent change versus percent difference?
Percent change compares a new value with an old one. Percent difference compares two values with no before and after, using their average as the base.