A percentage is a number expressed as a fraction of 100. This calculator solves the three questions people ask most often: what a given percent of a number is, what percent one number is of another, and what the whole is when you only know a part and its percentage.
How to use the percentage calculator
- Choose the question you want to answer from the drop-down.
- Enter the two numbers you know.
- The answer updates instantly — use “Share result” to send the exact calculation to someone.
Formula
Part = (Percent ÷ 100) × Whole
Rearrange the same formula to solve the other two questions: Percent = Part ÷ Whole × 100, and Whole = Part ÷ (Percent ÷ 100).
Worked example
What is 20% of 150? Convert 20% to a decimal (0.20) and multiply: 0.20 × 150 = 30.
30 is what percent of 150? Divide and multiply by 100: 30 ÷ 150 × 100 = 20%.
Frequently asked questions
How do I calculate a percentage of a number?
Divide the percentage by 100 to get a decimal, then multiply it by the number. For example, 15% of 80 is 0.15 × 80 = 12.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 12 out of 80 is 12 ÷ 80 × 100 = 15%.
Can a percentage be more than 100%?
Yes. A value larger than the whole is more than 100% of it — for example, 150 is 300% of 50.
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