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Percentage calculator

Type in any box: the answers and the working update as you go.

Percentage of a number

Answer 30

How we got this

  1. Turn the percentage into a decimal: 15% = 15 ÷ 100 = 0.15
  2. Multiply: 0.15 × 200 = 30
What percent is it?

Answer 15%

How we got this

  1. Divide the part by the whole: 30 ÷ 200 = 0.15
  2. Multiply by 100 to get a percentage: 0.15 × 100 = 15%
Find the whole

Answer 200

How we got this

  1. Turn the percentage into a decimal: 15% = 0.15
  2. Divide the part by it: 30 ÷ 0.15 = 200

Worked out on your device. Nothing is sent anywhere.

Three ways to ask about a percentage

A percentage is a number out of 100: 15% means 15 hundredths, or 0.15. Every everyday percentage question is one of the three above, and each is one multiplication or division:

QuestionFormulaExample
What is P% of Y?P ÷ 100 × Y15% of 200 = 30
X is what % of Y?X ÷ Y × 10030 of 200 = 15%
X is P% of what?X ÷ (P ÷ 100)30 is 15% of 200

Percentages above 100 work the same way (250% of 40 is 100), and so do negative numbers and decimals. The answers here are exact: the calculator never turns 0.1 into a slightly-wrong binary fraction the way spreadsheets and most calculators do.

Questions

How do I work out a percentage of a number?

Divide the percentage by 100 and multiply by the number. 15% of 200 is 0.15 × 200 = 30. A handy shortcut: 10% is the number divided by 10, so 15% is 10% plus half of that again.

How do I find what percent one number is of another?

Divide the part by the whole and multiply by 100. 30 out of 200 is 30 ÷ 200 = 0.15, which is 15%. A test score of 42 out of 50 is 42 ÷ 50 × 100 = 84%.

How do I find the original number from a percentage?

Divide the part by the percentage as a decimal. If 30 is 15% of something, that something is 30 ÷ 0.15 = 200. This is how you get a price before tax or a total from a share of it.

Is X% of Y the same as Y% of X?

Yes, always. 8% of 50 is 4, and 50% of 8 is also 4, because both are 8 × 50 ÷ 100. Swap them when one way round is easier to do in your head.

Why does an answer start with ≈?

The calculator works with the exact numbers you type, so 0.1 + 0.2 is exactly 0.3 here. When the exact answer never ends (30 ÷ 9 = 3.333…), it is rounded to 6 decimal places and marked with ≈.

How do I work out a percentage increase or decrease?

Use the percentage change calculator: it finds the change from one number to another, adds or takes off a percentage, and compares two numbers by percentage difference.

Is what I type saved or sent anywhere?

No. Every calculation happens in your browser. Your numbers appear in the page address only so you can bookmark or share the result.

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