What it does
This calculator works out a percentage of a number — for example, what 15% of 240 comes to. Type a percentage and a value and the answer appears as you go; there is no button to press and nothing is sent to a server.
How it works
A percentage is just a fraction out of 100. To find a percentage of a value, you turn the percentage into a decimal (divide it by 100) and multiply:
Dividing by 100 rescales the percentage to a proportion between 0 and 1, and multiplying applies that proportion to your value. It is the same arithmetic whether you are taking 20% off a price or adding 2.5% interest.
Worked example
Take 15% of 240. First convert the percentage to a decimal: 15 ÷ 100 = 0.15. Then multiply by the value: 0.15 × 240 = 36. So 15% of 240 is 36.
Common uses
- Discounts: a "15% off" label on something priced 240 means a saving of 36.
- Tips and service: working out a 10% or 12.5% tip on a restaurant bill.
- Tax and interest: adding VAT, or estimating interest on a balance.
- Test scores and stats: turning "36 out of 240" into a percentage, or the reverse.
Frequently asked
How do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. For example, 36 out of 240 is (36 ÷ 240) × 100 = 15% — the inverse of the worked example above.
Can I use decimals, like 2.5%?
Yes. Fractional percentages work exactly the same way: 2.5% of 1000 is 0.025 × 1000 = 25.
What is 100% of a number?
100% of any value is the value itself, because dividing 100 by 100 gives 1, and multiplying by 1 changes nothing.