Percentage Calculator
Four common percentage calculations in one place. Fill in the numbers and the answer appears instantly.
What is X% of Y?
X is what percent of Y?
Percentage change from X to Y
Increase or decrease Y by X%
Formula
X is what % of Y = X / Y x 100
% change = (New - Old) / Old x 100
Increase by X% = Y x (1 + X / 100)
How percentages work
A percentage is a number out of 100. To find 15% of 200, multiply 200 by 0.15 to get 30. To turn a result back into a percent, divide the part by the whole and multiply by 100.
Percentage change example
A price rising from 80 to 100 is a change of (100 - 80) / 80 x 100 = 25% increase. Going back from 100 to 80 is only a 20% decrease, because the starting value is different.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. 15% of 200 is 0.15 x 200 = 30.
How do I calculate percentage increase?
Subtract the old value from the new value, divide by the old value, then multiply by 100.
Why is a 20% rise not undone by a 20% fall?
The second percentage applies to a larger number, so it removes more than the first added. A 20% rise followed by a 20% fall leaves you 4% lower.
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