Quick answer: Divide the part by the whole and multiply by 100: 30 is 30 ÷ 200 × 100 = 15% of 200.
How it's calculated
The question "X is what percent of Y?" compares a part with the whole. The answer is X ÷ Y × 100. If you scored 42 out of 50, your mark is 42 ÷ 50 × 100 = 84%.
Put the whole in the second box. If you swap them you answer a different question: 200 is 666.67% of 30, not 15%.
The part can be bigger than the whole, which gives more than 100%: sales of 150 against a target of 120 are 125% of target. The whole can't be 0, because you can't divide by zero. Results are shown to 2 decimal places, so 1 out of 3 shows as 33.33%.
To go the other way and find a given percentage of a number, use the percentage calculator. To compare an old and a new value, use the percentage change calculator, and for a price cut the discount calculator.
Worked examples
- 30 out of 200: 30 ÷ 200 × 100 = 15%
- An exam mark of 42 out of 50: 42 ÷ 50 × 100 = 84%
- Rent of 4,500 SAR from a salary of 12,000 SAR: 4,500 ÷ 12,000 × 100 = 37.5%
Marks out of 50 as a percentage
Each mark is divided by 50 and multiplied by 100:
| Mark out of 50 | Percentage |
|---|---|
| 25 | 50% |
| 35 | 70% |
| 40 | 80% |
| 42 | 84% |
| 45 | 90% |
Frequently asked questions
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. 30 out of 200 is 30 ÷ 200 × 100 = 15%.
How do I turn an exam mark into a percentage?
Divide your mark by the maximum mark and multiply by 100. 42 out of 50 is 84%, and 35 out of 50 is 70%.
Can the answer be more than 100%?
Yes, when the part is bigger than the whole. 150 against a target of 120 is 150 ÷ 120 × 100 = 125%.
Why does 1 out of 3 show 33.33%?
The exact answer is 33.333…%, which never ends, so it is rounded to 2 decimal places. The page says when a result has been rounded.
What if the total is 0?
There is no answer, because you can't divide by zero. The calculator shows a message instead of a result.
What share of my salary goes on rent?
Divide the rent by the salary and multiply by 100. 4,500 out of 12,000 is 37.5%.
Is what I type sent anywhere?
No. It's plain arithmetic done in your browser. Nothing is uploaded or saved, and the numbers don't appear in the address bar.