Percentage Calculator

To find a percentage of a number, divide the percentage by 100 and multiply by the number. For example, 20% of 150 is 0.20 × 150 = 30. In this calculator, open the "What is X% of Y?" tab, type 20 as the percentage and 150 as the total amount, and the answer appears right away.

Divide the part by the whole and multiply by 100. For example, 45 out of 60 is (45 / 60) × 100 = 75%. Use the "X is what % of Y?" tab, enter 45 as the Number (X) and 60 as the Total (Y). The result is shown with two decimal places.

Percentage change is the difference between the new and old value, divided by the old value, times 100. Going from 80 to 100 is ((100 − 80) / 80) × 100 = 25% increase. Going from 100 to 80 is a 20% decrease. The calculator labels the result as an increase or decrease for you.

Because each percentage is based on a different starting value. If 100 rises by 50%, it becomes 150. A 50% decrease from 150 removes 75, leaving 75, not 100. The base changes after the first step, so equal percentage moves up and down do not cancel each other out.

Yes, you can type decimal values and negative numbers in any field. For the percentage change tab, the initial value cannot be zero, because dividing by zero has no answer; in that case the result stays at 0%. For the "X is what % of Y?" tab, the total must also be a non-zero number.