Percentage Calculator
Three percent questions, each with its own answer: what is X% of Y, X is what percent of Y, and X is Y% of what. Every result shows the math.
What is X% of Y?
20% of 150 is
30
| 20% as a decimal (20 ÷ 100) | 0.2 |
|---|---|
| 0.2 × 150 | 30 |
X is what percent of Y?
30 is this percent of 150
20%
| 30 ÷ 150 | 0.2 |
|---|---|
| × 100 | 20% |
X is Y% of what?
30 is 20% of
150
| 20% as a decimal (20 ÷ 100) | 0.2 |
|---|---|
| 30 ÷ 0.2 | 150 |
How this is calculated
A percent is a number out of 100: 20% means 20 per 100, or 0.2 as a decimal. Each of the three questions is one multiplication or one division.
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | X ÷ 100 × Y | 20% of 150 = 0.2 × 150 = 30 |
| X is what percent of Y? | X ÷ Y × 100 | 30 ÷ 150 × 100 = 20% |
| X is Y% of what? | X ÷ (Y ÷ 100) | 30 ÷ 0.2 = 150 |
Percents above 100 work the same way: 150% of 40 is 1.5 × 40 = 60. A negative percent or a negative number gives a negative result.
Two questions have no answer. “What percent of 0” would mean dividing by zero, and “X is 0% of what” has no answer because 0% of every number is 0. The calculator says so instead of showing a number. Results are shown with up to four decimal places.
A shortcut for mental math: X% of Y is the same as Y% of X. 8% of 50 is hard to see, but 50% of 8 is 4, and so is 8% of 50.
Increase, decrease and change
For “what is the percent increase from 80 to 100” or “add 15% to 60”, use the percent change calculator.
Questions people ask
How do I calculate a percentage of a number?
Divide the percent by 100 and multiply by the number. 15% of 80 is 0.15 × 80 = 12.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. 18 out of 24 is 18 ÷ 24 × 100 = 75%.
How do I find the whole if I know a part and its percent?
Divide the part by the percent written as a decimal. If 30 is 20% of a number, the number is 30 ÷ 0.2 = 150.
Is X% of Y the same as Y% of X?
Yes. Both are X × Y ÷ 100, so 8% of 50 and 50% of 8 are both 4.
Can a percentage be more than 100?
Yes. 150% of 40 is 60. Only a share of a fixed whole, like a test score without extra credit, stops at 100%.