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Percentage calculator
Find a percentage of a number, what percent one number is of another, and the percentage increase or decrease.
What is X% of Y?
X is what percent of Y?
Percentage increase or decrease
Add or subtract a percentage
What is the percentage calculator used for?
A percentage expresses a number as a part of 100. Percentages are used for marks and grades, discounts, interest, taxes, profit, growth and almost every comparison between two numbers. A percentage calculator saves you from working out the fractions by hand.
This page has four calculators in one: the percentage of a number, what percent one number is of another, the percentage change between an old and a new value, and adding or subtracting a percentage. Each result is shown with the formula used.
Why use this one
All the common percentage questions are on one page, each with its formula so students can check their working. It runs in your browser, needs no sign-up, and recalculates as you type.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 640 is 640 × 15 ÷ 100 = 96.
How do I find what percent one number is of another?
Divide the first number by the second and multiply by 100. For example, 45 out of 150 is 45 ÷ 150 × 100 = 30%.
How do I calculate percentage increase?
Percentage change = (new value − old value) ÷ old value × 100. A rise from 80 to 100 is (100 − 80) ÷ 80 × 100 = 25%.
Why is a 50% rise followed by a 50% fall not back to the start?
The fall is calculated on the larger, increased value. A price of 100 rising 50% becomes 150, and falling 50% from 150 gives 75, not 100.
How do I work out my exam percentage?
Add up the marks you scored, divide by the total marks and multiply by 100. For 432 marks out of 500, the percentage is 432 ÷ 500 × 100 = 86.4%.