Calculate a percentage of a number
Percent means per hundred. Divide the percentage by 100, then multiply by the number. For 18% of 250, use 18 ÷ 100 × 250 = 45. This works for a tip, a project allowance, or a portion of a total.
Percentage Calculator
Answer the everyday “what percent?” question. Choose the relationship you know, enter two values, and see the answer with the arithmetic.
Percentage Calculator
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How to use this calculator
Find what percentage one number represents
To find what percent 45 is of 60, divide the part by the reference number and multiply by 100: 45 ÷ 60 × 100 = 75%. Choose “A is what percent of B?” and enter 45, then 60. The reference number must not be zero.
Recover the original whole
If 45 represents 18% of an unknown whole, divide 45 by 0.18 to get 250. Choose “A is B% of what?” for this calculation. A percentage of zero does not identify a unique original whole.
Read the comparison carefully
A percentage of a reference number is different from a percentage share of a combined total. For example, 3 is 150% of 2, but 3 is 60% of the combined total 5. Use our ratio-to-percentage tool when the values represent separate parts of one whole.
A LITTLE MORE CLARITY
Common questions
Can a result exceed 100%?
Yes. If the part is larger than the reference, its percentage exceeds 100%. For example, 150 is 125% of 120.
Can I enter decimals?
Yes. Enter ordinary decimal numbers without percent signs, currency symbols, or commas. Results are rounded for display.
About this tool
Created by Marchelle Cook at Roof & Ratio. These calculations run in your browser; entered values are not uploaded or saved by the calculator. Report a calculation issue with an example so we can review it.
Guide updated October 23, 2026. Displayed decimal results may be rounded; exact fraction and integer results are identified in the answer.