Percentage calculator

Pick the question you are trying to answer, enter two numbers, and see the steps.

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Percent of a number

To find X% of Y, divide X by 100 and multiply by Y. So 15% of 200 is 0.15 × 200 = 30. To go the other way, divide the part by the whole and multiply by 100.

Percent change

Percent change is (new − old) ÷ old × 100. A positive result is an increase and a negative result is a decrease. Note that going up 50% and then down 50% does not return you to the start, because the second percentage is taken from a bigger number.

Increase and decrease

To raise a value by Y%, multiply it by 1 + Y/100. To lower it, multiply by 1 − Y/100. This is how sales prices, tips, and tax are worked out.

Percentage points

If a rate moves from 20% to 25%, it rose by 5 percentage points, which is a 25% relative increase. Teachers and textbooks use these two ideas differently, so check which one a question wants.