How to use this calculator
A percentage expresses a quantity per hundred. First identify the whole: it is the reference amount, and it does not have to be the larger number. Use the third mode when you know a part and its percentage but need the original total.
Which percentage calculation do you need?
| Your question | Mode | Inputs | Result |
|---|---|---|---|
| What is 18% of 350? | Percentage of a number | Percentage 18; whole 350 | 63 |
| 42 is what percent of 60? | What percent is A of B? | Part 42; whole 60 | 70% |
| 54 is 15% of what number? | Find the original whole | Percentage 15; known part 54 | 360 |
The “Try an example” buttons above load these questions into the calculator. The whole is the reference quantity: if 42 questions are correct out of 60, divide 42 by 60, then multiply by 100. Dividing 60 by 42 answers a different question.
When the part is larger than the whole
If a target is 80 and the actual amount is 120, the actual amount is 150% of the target. This is valid: percentages are not limited to 100%. The increase above the target is 50%, calculated by percentage change.
If you already know a rate and want to add or subtract it, use percentage increase and decrease. For sale prices and successive discounts, use the discount calculator.
The formula
Worked examples
A 15% share of 240
15 / 100 × 240 = 36.
36 is what percent of 240?
36 / 240 × 100 = 15%.
36 is 15% of which total?
36 / 0.15 = 240.
Special cases & input limits
Zero percent of any finite number is zero. A zero whole cannot be a denominator. Recovering a whole from 0% has no unique answer, even when the known part is zero. Negative inputs and percentages above 100 are allowed.
Inputs support a decimal point and scientific notation, up to 30 significant digits and a magnitude of 10⁻²⁰ to 10³⁰, or zero. Select 0–12 display decimal places. Very small or large answers use scientific notation so a nonzero result is not displayed as zero.
A common mistake
Dividing the whole by the part reverses the question. A part of 120 out of a whole of 80 is 150%, not 66.67%.
Content updated · Calculation methodology