Free Percentage Calculator
Three percentage calculators in one — results appear as you type.
What is X% of a number?
% of
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X is what percent of Y?
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Percent increase / decrease
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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. For example, 15% of 200 is 200 × 15 ÷ 100 = 30. The first calculator above does this instantly.
How do I work out a percent increase?
Subtract the old value from the new, divide by the old value, then multiply by 100. Going from 80 to 100: (100 − 80) ÷ 80 × 100 = 25% increase. A negative result means a decrease.
Why is a 50% increase not undone by a 50% decrease?
Because the percentage applies to a different base each time. 100 increased 50% is 150; 150 decreased 50% is 75, not 100. The bigger the change, the bigger this asymmetry.
How do I add a percentage to a price (like tax)?
Multiply by 1 plus the rate: adding 8% tax to $50 is 50 × 1.08 = $54. For discounts, multiply by 1 minus the rate. Our tip calculator handles restaurant math directly.