Percent of a number calculator
Work out a percentage of any number instantly, or the number with that percentage added or taken off.
Percent of a number calculator: what it is and how it works
Per cent means how many units out of every hundred we take from an amount. It is a simple but very common calculation: tips, commissions, surcharges, pay rises or the share of a budget for each item.
To find X % of a number, multiply the number by X and divide by 100 — or multiply by the decimal equivalent (X ÷ 100). To add a percentage, multiply by (1 + X ÷ 100); to subtract it, by (1 − X ÷ 100). This calculator does all three and also shows the value of the percentage and its decimal and fraction equivalents.
How to use it
- Choose whether to find, add or subtract the percentage.
- Enter the percentage and the number.
- Read the result and the value of the percentage.
X % of N = N × X ÷ 100 · N + X % = N × (1 + X ÷ 100) · N − X % = N × (1 − X ÷ 100)Worked example
15 % of 200 is 30. 200 plus 15 % is 230, and 200 minus 15 % is 170. 15 % is 0.15 as a decimal.
Frequently asked questions
How can I work out a percentage in my head?
Find 10 % by moving the decimal point one place, then adjust: 15 % is 10 % plus half of 10 %. So 15 % of 200 is 20 + 10 = 30.
What is the decimal equivalent of a percentage?
The percentage divided by 100. 21 % is 0.21, and multiplying by 0.21 is the same as taking 21 %.
How do I add a percentage to a price?
Multiply the price by 1 plus the decimal. To add 10 % to €50: 50 × 1.10 = €55.
What if the percentage is already included?
Then divide instead of subtracting: a €110 price including 10 % is 110 ÷ 1.10 = €100 before it.