Percentage calculator

How to use the percentage calculator

1. Choose "X% of Y" or "X is what % of Y".
2. Type the two numbers into the boxes.
3. Read the answer, which updates as you type.

The two percentage sums, with examples

Finding a percentage of a number: divide the percentage by 100 and multiply. 15% of £240 is 0.15 x 240 = £36. 12.5% of 3,200 is 0.125 x 3,200 = 400.

Finding what percentage one number is of another: divide the part by the whole and multiply by 100. If you scored 45 out of 60, that is 45 / 60 x 100 = 75%. If £180 of your £1,200 monthly budget goes on food, that is 180 / 1,200 x 100 = 15%.

The order matters in the second sum. The "whole" goes on the bottom. 45 is 75% of 60, but 60 is 133.3% of 45.

Quick ways to do percentages in your head

• 10%: move the decimal point one place left. 10% of £84 is £8.40.
• 5%: half of 10%. 5% of £84 is £4.20.
• 1%: move the decimal point two places. 1% of £84 is £0.84.
• 25%: divide by 4. 50%: halve it.

Build other percentages from those. 15% is 10% plus 5%, so 15% of £84 is £8.40 + £4.20 = £12.60. 17.5% of £200 is £20 + £10 + £5 = £35.

Percentages also swap round: 8% of 50 is the same as 50% of 8, which is 4. When one way looks hard, try the other.

Working backwards from a percentage

If you know the part and the percentage, divide the part by the percentage and multiply by 100 to find the whole. If £36 is 15% of a bill, the bill is 36 / 15 x 100 = £240. This is the same thinking behind taking VAT off a price, which has its own calculator on this site.

Questions people ask