Percentage Calculator

Solve the three common percentage questions — percent of, is what percent, and percentage change.

The percent, e.g. 20 for 20%.

The number you want a percentage of.

Result—

Enter your values and calculate to see the result.

Formula used

X% of Y:              result = (X ÷ 100) × Y
X is what % of Y:     result = (X ÷ Y) × 100
Change from X to Y:   result = ((Y − X) ÷ X) × 100
                      (positive = increase, negative = decrease)
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Worked example

Mode: Percentage change from 80 to 100

(100 − 80) ÷ 80 × 100 = 20 ÷ 80 × 100 = 25%

Result: a 25% increase.

Frequently asked questions

What does each mode do?

There are three modes. X% of Y finds a portion of a number (20% of 250 = 50). X is what % of Y expresses one number as a percent of another (25 of 200 = 12.5%). Change from X to Y gives the percentage increase or decrease between a start and end value.

How is percentage change calculated?

Percentage change is (end − start) ÷ start × 100. A positive result is an increase and a negative result is a decrease. Because it divides by the start value, the start cannot be zero.

Why can't the whole or start value be zero?

Both the "is what percent" and "percentage change" formulas divide by that value, and division by zero is undefined. The calculator shows a message instead of a misleading number when you enter zero there.

Does it accept decimals and negative numbers?

Yes. You can enter decimals (such as 12.5) and negative values where they make sense — for example a percentage change from a positive to a negative value.