Percentage Calculator

What is a percentage?

A percentage describes a number as a fraction of 100. The symbol % means “per hundred”: 35% is the same as 35 out of 100, 0.35 as a decimal, or 7/20 as a fraction.

How to calculate a percentage

To find a percentage of a number, divide the percentage by 100 and multiply it by the number. For example, 15% of 240 is 0.15 × 240, which equals 36.

The basic relationship is: percentage × original value = result. When working it out by hand, use the percentage as a decimal. For example, if 5% of 30 is 1.5, then 0.05 × 30 = 1.5.

How to find what percentage one number is of another

Divide the first number by the second number, then multiply by 100. For example, 30 is what percentage of 120? Calculate 30 ÷ 120 × 100 = 25%.

How to find the whole number

When you know the part and the percentage it represents, divide the part by the percentage as a decimal. For example, if 10 is 5% of a number, the whole is 10 ÷ 0.05 = 200.

Increasing or decreasing a number by a percentage

To increase a value, multiply it by 1 plus the percentage as a decimal. To decrease a value, multiply it by 1 minus the percentage as a decimal. For example, increasing 500 by 10% gives 500 × 1.10 = 550; decreasing it by 10% gives 500 × 0.90 = 450.

Everyday percentage examples

Percentages are useful for working out discounts, VAT, test scores, progress towards a target and how much of a monthly budget is spent on one cost. For example, if rent is £1,245 and a monthly budget is £4,000, rent uses 31.125% of that budget.

Percentage points are not the same as a percentage change

If a rate moves from 10% to 12%, it has risen by 2 percentage points. Relative to the original 10%, that is a 20% increase. The distinction matters when comparing interest rates, surveys and statistics.