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% Percentage Calculator

Three ways to calculate percentages: find a percent of a number, find what percent one number is of another, or find percentage change.

What is X% of Y?

Result

20% of 150 is 30

Percentage Formulas

A percentage expresses a number as a fraction of 100. This calculator covers the three most common percentage problems.

X% of Y

Result = (X ÷ 100) × Y

X is what percent of Y

Result = (X ÷ Y) × 100

Percentage change from X to Y

Change % = ((Y − X) ÷ X) × 100

A positive result is a percentage increase; a negative result is a percentage decrease.

Frequently Asked Questions

How do I calculate a percentage increase?

Subtract the original value from the new value, divide by the original value, then multiply by 100. A positive result means an increase.

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

Divide the first number by the second, then multiply by 100. For example, 30 is 20% of 150 because (30 ÷ 150) × 100 = 20.

What if the "from" value in percentage change is zero?

Percentage change is undefined when the starting value is zero, since you cannot divide by zero. The calculator will show a validation note in that case.