How to use this calculator
- Enter or choose question.
- Enter or choose a.
- Enter or choose b.
- The answer updates as you type. Use Copy result or Share to keep it.
Formula
Part = Percent ÷ 100 × Whole; Percent = Part ÷ Whole × 100; Whole = Part ÷ (Percent ÷ 100)
- Part
- the share you have
- Whole
- the total it is a share of
- Percent
- the share per hundred
Worked example
- 20% of 150 = 20 ÷ 100 × 150.
- = 0.2 × 150 = 30.
- Check the other way: 30 is 30 ÷ 150 × 100 = 20% of 150.
20% of 150 is 30.
What the result means
Choose the question that matches what you know. A quick mental check: 10% is the number with the decimal point moved one place left, so 20% of 150 is twice 15.
Assumptions and limits
- For changes between two values, use the percentage change calculator; “percent of” and “percent change” answer different questions.
Questions
How do I calculate a percentage of a number?
Divide the percentage by 100 and multiply by the number. 15% of 80 is 0.15 × 80 = 12.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. 18 out of 24 is 18 ÷ 24 × 100 = 75%.
Is X% of Y the same as Y% of X?
Yes. 8% of 50 and 50% of 8 are both 4, which sometimes makes mental maths easier.