Math · 3 min read
How to Calculate Percentages
The three percentage questions that come up most — percent of a number, percentage change, and what percent one number is of another.
Try the percentage calculatorPut these numbers to workOpen →A percentage is just a fraction of 100. Almost every real-world percentage question is one of three types, and each has a simple formula.
Percent of a number
X% of Y = (X ÷ 100) × Y. Example: 20% of 80 = 0.20 × 80 = 16.
Percentage change
Change = (new − old) ÷ old × 100. Example: from 200 to 250 is (250 − 200) ÷ 200 × 100 = +25%.
A positive result is an increase; a negative result is a decrease.
What percent is X of Y
Percent = X ÷ Y × 100. Example: 30 out of 120 is 30 ÷ 120 × 100 = 25%.
Where you'll use these
- •Tips and sales tax on a bill
- •Discounts and markups on a price
- •Growth or decline between two figures
- •Test scores and progress
- 1Pick the mode that matches your question.
- 2Enter the two numbers.
- 3Read the answer — it updates as you type.