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Percentage Calculator – Percent Of, % Change and X Out of Y

Four percentage calculators in one: find X% of a number, what percent one number is of another, the percentage change between two values, and a number plus or minus a percentage.

Quick answer

To find X% of a number, multiply the number by X and divide by 100: 15% of 80 = 80 × 15 ÷ 100 = 12. To find what percent A is of B, divide A by B and multiply by 100: 12 ÷ 80 × 100 = 15%.

How to use the Percentage Calculator

  1. Pick the question you want to answer from the tabs.
  2. Type the two numbers — decimals are fine.
  3. Read the answer and the full sentence below it, then copy the result with one tap.

Percentage formulas

  • X% of Y = Y × X ÷ 100
  • X is what % of Y = X ÷ Y × 100
  • Percentage change from A to B = (B − A) ÷ |A| × 100
  • Add X% to Y = Y × (1 + X ÷ 100); remove X% = Y × (1 − X ÷ 100)

Worked examples

Test score: 11 out of 15 = 11 ÷ 15 × 100 = 73.33%.

Price change: a price going from 40 to 50 is a (50 − 40) ÷ 40 × 100 = 25% increase. Going back from 50 to 40 is a 20% decrease — percentage changes are not symmetrical.

Sale price: 30% off 120 = 120 × 0.7 = 84.

Percentage points vs percent

If an interest rate rises from 2% to 3%, it rose by 1 percentage point, but by 50 percent. Use the % change tab for the second number.

Related tools: Hours Calculator, Time Converter and Age Calculator.

Popular pages

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Frequently asked questions

How do I calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. 20% of 250 = 250 × 20 ÷ 100 = 50.

How do I work out what percent one number is of another?

Divide the first number by the second and multiply by 100. 18 out of 24 = 18 ÷ 24 × 100 = 75%.

How do I calculate percentage increase?

Subtract the old value from the new value, divide by the old value and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 × 100 = 25%.

What is the percentage decrease formula?

Percentage decrease = (old − new) ÷ old × 100. From 100 to 85 is a 15% decrease.

How do I remove VAT or a percentage from a price?

To remove a percentage that was added, divide by (1 + rate). A price of 121 including 21% VAT is 121 ÷ 1.21 = 100 before tax.

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