Choose the part and the whole
The part is the amount you want to compare. The whole is the reference total. For example, if 18 questions out of 120 were answered correctly, 18 is the part and 120 is the whole.
The equation
Percentage = part ÷ whole × 100
Verified example
Enter 18 for Part and 120 for Whole. The calculation is 18 ÷ 120 × 100 = 15%, which is the value displayed by the tool.
Common mistakes
- Do not reverse the values.
120 ÷ 18 × 100answers a different question. - The whole cannot be zero. Dividing by zero does not produce a meaningful percentage.
- A result above 100% can be correct when the part is larger than the reference whole.
- Use the same unit for both values. Comparing dollars to items, for example, does not answer a percentage question without another conversion.
The calculator rounds its displayed answer to two decimal places when needed. Keep more precision in your source figures if a small difference matters.