How to Calculate Percentages

What a percentage means

A percentage expresses a part of something out of 100. If 25 out of 100 items are orange, 25% are orange.

How to find a percentage of a number

Convert the percentage to a decimal and multiply it by the number. For example, 15% of 240 is 0.15 × 240 = 36.

How to calculate percentage increase

Subtract the original value from the new value, divide by the original value, then multiply by 100.

Common mistakes

A common mistake is dividing by the new value instead of the original value when calculating percentage change.

Quick percentage shortcuts

Some percentages are easy to estimate mentally. Ten percent is one tenth of a number, 5% is half of 10%, and 1% is one hundredth. You can combine these: 15% is 10% plus 5%, while 25% is one quarter.

These shortcuts are useful for checking a calculator result. If the answer is far away from your quick estimate, check that the percentage and number were entered in the right fields.

Percentage points vs percentage change

Percentage points are used when comparing two percentages directly. If a rate rises from 20% to 25%, it has increased by 5 percentage points. The percentage increase is different: the increase of 5 divided by the original 20 equals a 25% increase.

How to calculate a discount

To calculate a discount, first find the discount percentage of the original price, then subtract that amount from the original price. For example, 20% of £80 is £16, so an item reduced by 20% costs £64.

If you only need the final price, you can multiply by the percentage that remains. After a 20% discount, 80% remains, so £80 × 0.80 = £64.

Quick percentage examples

20% of 350 is 70. 15% of £60 is £9. To find what percentage 20 is of 80, calculate 20 ÷ 80 × 100 = 25%.

Use the UsefulFox Percentage Calculator for quick percentage calculations.

Frequently asked questions