How to use the What Percent Calculator
- Enter the part, the smaller number you want to express as a percentage.
- Enter the whole, the total it belongs to.
- Read the percentage that the part makes up of the whole.
Formula used
Percentage = (Part ÷ Whole) × 100.
Worked example
Here is the What Percent Calculator worked through with the example values shown above, so you can check each step by hand.
| Inputs | |
|---|---|
| Part (X) | 30 |
| Whole (Y) | 200 |
| Result | |
| X as a percentage of Y | 15% |
How to 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%. 45 out of 60 is 75%, and 42 out of 56 is also 75%.
The part can be larger than the whole. If you sold 250 units against a target of 200, the result is 125%, which means you exceeded the target by a quarter.
Everyday examples
Exam marks: 432 out of 500 is 86.4%. Attendance: 42 present out of 56 classes is 75%. Savings: if you save ₹12,000 out of a monthly income of ₹60,000, you save 20%. Business: if 18 out of 240 products are returned, the return rate is 7.5%.
To work backwards, divide the part by the percentage as a decimal to find the whole. If 15% of a number is 30, the number is 30 ÷ 0.15 = 200.
Common mistakes
The most frequent error is swapping the part and the whole. 30 is 15% of 200, but 200 is 666.7% of 30. Another is forgetting to multiply by 100 and reading 0.15 as the answer. Keep the part on top and the whole at the bottom, and the result will make sense.
Order matters, and other common mistakes
The question “X is what percent of Y?” divides the part by the whole, so the order of the numbers changes the answer. 25 is 50% of 50, but 50 is 200% of 25. Always put the number you are describing first and the reference number second.
Another common mistake is to confuse percent with percentage points. If a rate rises from 4% to 6%, it has risen by 2 percentage points, but by 50% in relative terms (2 ÷ 4). Use the percentage change calculator on this site to measure how much a value has risen or fallen between two numbers.
Frequently asked questions
How do I find what percent one number is of another?
Divide the first number by the second and multiply by 100. For 30 out of 200, 30 ÷ 200 × 100 = 15%.
How do I calculate my marks percentage?
Divide the marks you obtained by the total marks and multiply by 100. 432 out of 500 is 86.4%.
How do I calculate attendance percentage?
Divide the classes attended by the total classes held and multiply by 100. 42 out of 56 classes is 75% attendance.
Can the answer be more than 100%?
Yes, if the part is larger than the whole. 250 out of 200 is 125%.
How do I find the total if I know the percentage and the part?
Divide the part by the percentage as a decimal. If 15% of a number is 30, the number is 30 ÷ 0.15 = 200.
What is the difference between this and the percentage calculator?
This one finds what percent a number is of another. The percentage calculator does the opposite: it finds the value of a given percent of a number, such as 15% of 200.
Why does swapping the two numbers change the answer?
Because the result is the first number divided by the second. 25 ÷ 50 is 50%, but 50 ÷ 25 is 200%.
This calculator gives estimates for information only. Actual figures from a bank, employer, tax authority or doctor may differ. It is not financial, tax, legal or medical advice.