Percentage Calculator
What is X% of Y?
Result
20
X is what % of Y?
Percentage
12.50%
Percentage Change
Change
50.00%
increase
How it works
The percentage calculator handles the three percentage questions people ask most often, each in its own box. The first answers "What is X% of Y?" by working out (X / 100) x Y. The second answers "X is what percent of Y?" by working out (X / Y) x 100. The third finds the percentage change between two values using ((new - old) / |old|) x 100, where |old| is the starting value without its minus sign.
Results update as you type. Plain results are shown with up to two decimal places, and percentages are rounded to two decimal places. In the percentage change box, the result is shown as a positive number with a label telling you whether it is an increase (green) or a decrease (red).
A few edge cases are worth knowing. You can't take a percentage of a total of zero, and you can't measure a change starting from zero, because both would mean dividing by zero; in those cases the calculator tells you the answer is undefined instead of showing a number. Because the change formula divides by the starting value, going from 50 to 100 is a 100% increase, while going from 100 back to 50 is a 50% decrease.
Frequently asked questions
How do I calculate 15% of a number?+
Divide 15 by 100 and multiply by the number. For example, 15% of 80 is 0.15 x 80 = 12. Enter 15 and 80 in the first box to get the answer instantly.
How do I find what percent one number is of another?+
Divide the part by the total and multiply by 100. For example, 25 out of 200 is (25 / 200) x 100 = 12.5%.
How do I calculate percentage increase or decrease?+
Subtract the old value from the new value, divide by the old value, and multiply by 100. Going from 100 to 150 is a 50% increase; going from 150 to 100 is a 33.33% decrease.
Why isn't a 50% increase cancelled out by a 50% decrease?+
Each percentage is measured against a different starting value. 100 plus 50% is 150, but 150 minus 50% is 75, because the decrease is taken from the larger number.