About the Percentage Calculator

The Percentage Calculator answers the three questions people ask most often: what is a percentage of a number, what percent one number is of another, and by what percent a value has changed. All three results update as you type.

Use it for exam marks, sales discounts, tips, tax, salary changes, price rises, statistics, or any time you need a quick percentage without opening a spreadsheet.

How to use the Percentage Calculator

Choose the block that matches your question.
Type the two numbers into the fields. Decimals are fine.
The answer appears straight away below the fields.
Change a number to see the result update.

How it works

To find a percentage of a number the tool multiplies the number by the percentage and divides by 100. To find what percent one number is of another it divides the first by the second and multiplies by 100. For percentage change it subtracts the old value from the new value, divides by the old value and multiplies by 100.

A positive change is an increase and a negative change is a decrease. If the old value is zero, a percentage change cannot be defined and the tool tells you so.

Frequently asked questions

How do I calculate a percentage increase?

Use the third block. Enter the old value first and the new value second. A result of 25 means the value went up by 25 percent.

How do I work out a tip or a discount?

Use the first block. For a 15 percent tip on 80, enter 15 and 80 to get 12. For a 20 percent discount on 250, enter 20 and 250 to get 50, which you subtract from the price.

Why is a 50 percent rise followed by a 50 percent fall not back to the start?

The second change is applied to a larger number. A rise of 50 percent takes 100 to 150, and a fall of 50 percent from 150 takes it to 75, not 100.