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OZO Percentage Calculator

Free Percentage Calculator

Work out a percentage of a number, what percent one number is of another, or the percentage increase or decrease between two numbers.

  • Free forever
  • No signup
  • Instant results
Which calculation?
%

Enter two numbers to see the answer.

How to calculate percentages

  1. 1

    Pick your question

    Choose “X% of Y”, “X is what % of Y” or “% change”.

  2. 2

    Enter the two numbers

    Type the numbers into the two fields; the labels change to match the question.

  3. 3

    Read the answer

    The result appears instantly. For a change, it shows whether it is an increase or a decrease.

Three everyday percentage questions

Most percentage problems are one of three kinds: finding a percentage of something (a tip, a commission, a tax), finding what share one number is of another (a score, a conversion rate), or measuring the change between two numbers (a price rise, sales growth). Pick the mode that matches and the calculator does the rest.

Formulas

  • X% of Y = Y × X ÷ 100
  • X as a percent of Y = X ÷ Y × 100
  • % change = (new − old) ÷ old × 100

Working with prices? The discount calculator and the profit margin calculator handle the most common business percentages.

For growth over many years, where percentages compound, use the compound interest calculator.

Frequently asked questions

How do I work out a percentage of a number?

Multiply the number by the percentage and divide by 100. 15% of 80 is 80 × 15 ÷ 100 = 12.

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

Divide the part by the whole and multiply by 100. 30 out of 120 is 30 ÷ 120 × 100 = 25%.

How do I calculate percentage increase or decrease?

Subtract the old value from the new one, divide by the old value and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 × 100 = 25% increase; from 100 to 80 is a 20% decrease.

Why is a 20% drop not undone by a 20% rise?

Because each percentage is taken from a different starting number. 100 minus 20% is 80, but 80 plus 20% is only 96. To get back to 100 you need a 25% rise.

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