Type a percentage and a number to find that percentage of it, for example 15% of 240. The result shows the working and what is left over.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How the Percentage of a number works
The rule is simple: x% of y = y × x ÷ 100. The tool divides the percentage by 100 to turn it into a decimal, then multiplies by the number.
Shown as steps:
- Divide the percentage by 100. For 15%, this gives 0.15.
- Multiply by the number.
The result also shows the remainder, which is the number minus the answer. That is useful when you want the amount left after taking a percentage off, such as a price after a discount.
You can use decimals, such as 7.5%, and percentages above 100%. A negative number works too, and gives a negative answer. The tool does not round the answer to money, so round the result yourself if you are working with pounds and pence.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Percentage | 15 % |
| Of the number | 240 |
15% of 240 is: 36
| Working | 15 ÷ 100 × 240 |
|---|---|
| Remainder | 204 |
Tips and common mistakes
To add a percentage to a number, work out the percentage and add it to the original. To take it off, use the remainder shown. For quick mental checks, find 10% by moving the decimal point one place left, then build up from there. If you need to go the other way, use the ‘what percent’ tool. Check that you have the right base number, since a percentage of the wrong total is the most common mistake.
Frequently asked questions
How do I work out a percentage of a number?
Divide the percentage by 100 and multiply by the number. So 15% of 240 is 0.15 × 240.
How do I find 10% quickly?
Divide the number by 10. You can then halve it for 5%, or double it for 20%, and add pieces together for other percentages.
Can I use percentages over 100%?
Yes. 150% of a number is one and a half times the number. The same formula works.