Percentage Calculator

Three percentage modes in one place: find a percentage of a number, express one number as a percentage of another, or calculate the percentage change between two values.

X% of Y

Percent (%)

Result

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X is what % of Y?

Percentage

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% change from A to B

From

% change

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How percentages work

A percentage is just a fraction out of 100. The three most common percentage questions are: how much is X% of a number, what percentage is one number of another, and by what percentage did something change.

Worked example. 25% of 80 is 20 (80 × 0.25). Flip it: 20 is 25% of 80 (20 ÷ 80 × 100). And going from 80 to 100 is a +25% change ((100 − 80) ÷ 80 × 100).

The formulas

X% of Y = Y × X ÷ 100

X is what % of Y = X ÷ Y × 100 (returns 0 if Y is 0)

% change from A to B = (B − A) ÷ A × 100 (returns 0 if A is 0)

Reading percentage change

A positive result means an increase; negative means a decrease. A 25% change from 80 to 100 and the same change from 100 to 80 are not mirror images — 100 to 80 is a −20% change, not −25%.

Frequently asked questions

How do I calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. For example, 25% of 80 is 80 × 25 ÷ 100 = 20.

How do I calculate percentage change?

Subtract the original value from the new value, divide by the original, then multiply by 100. An increase from 80 to 100 is (100 − 80) ÷ 80 × 100 = 25%.