How to use the Percentage Calculator tool
3 simple steps · under a minute
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Pick the question
Find the calculator that matches your question, for example “What is X% of Y?”.
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Type the numbers
Enter your values. The answer appears as you type.
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Check the working
Each answer shows the formula, so you can see exactly how it was calculated.
About Percentage calculator
Percentages come up everywhere: discounts, tips, tax, exam marks, salary rises and growth figures. This percentage calculator answers the five most common questions in one place, from “what is 20% of 150?” to “what is the percentage increase from 80 to 100?”.
Each answer shows the formula used, so you can follow the method and do it yourself next time.
Five calculators in one
Percent of a number, what percent, percentage change, and adding or removing a percentage.
Formula shown
Every result explains the maths, which makes it great for homework and checking work.
Instant answers
Results update while you type, with no button to press.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 20% of 150 = 150 × 20 ÷ 100 = 30.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 out of 150 = 30 ÷ 150 × 100 = 20%.
How is percentage change calculated?
Subtract the old value from the new value, divide by the old value and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 × 100 = 25% increase.
How do I calculate marks percentage?
Use “X is what percent of Y”: enter the marks you got as X and the total marks as Y.