Enter two numbers to find what percentage the first is of the second, for example 45 out of 180. The calculator shows the working and the answer as a decimal.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How the What percent works
To find what percentage one number is of another, divide the first by the second and multiply by 100:
percentage = part ÷ whole × 100
For 45 out of 180, you divide 45 by 180 to get 0.25, then multiply by 100 to get 25%. The tool also shows this decimal, which is useful when you want the fraction rather than the percentage.
The first box is the part, and the second box is the whole you are comparing it with. The whole cannot be zero, because you cannot divide by zero. The part can be larger than the whole, which gives a percentage over 100%.
This is a plain ratio calculation. It does not tell you the change between two values over time. For that, the percentage change tool uses the difference divided by the old value.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| This number | 45 |
| Is what percent of | 180 |
45 is this much of 180: 25%
| Working | 45 ÷ 180 × 100 |
|---|---|
| As a fraction | 0.25 |
Tips and common mistakes
Make sure the whole is the right way round. 45 out of 180 is 25%, but 180 out of 45 is 400%. Use this for test scores, shares of a budget, discounts and survey results. If the numbers have changed over time, use the percentage change tool instead, as it compares against the starting value. Round sensibly when you report the answer.
Frequently asked questions
How do I calculate what percent one number is of another?
Divide the first number by the second and multiply by 100. For 45 out of 180, 45 ÷ 180 × 100 = 25%.
Which number goes in which box?
The number you are measuring (the part) goes in the first box. The total you are comparing it with (the whole) goes in the second.
What if the first number is bigger than the second?
The answer is over 100%. For example, 180 is 400% of 45.