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Percentage calculator: part, whole and percent

Choose the missing quantity before calculating. “What is 15% of 240?”, “36 is what percent of 240?” and “36 is 15% of what?” are related questions, but they solve for different quantities.

Free to use, with no sign-in. Inputs and results stay in this page and are not sent with the form. Download a result before leaving; this tool does not save your work.

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Worked result

15% of 240 is 36.

  1. Convert 15% into 0.15.
  2. Multiply 0.15 by 240.
  3. The resulting part is 36.

Find 15% of 240

Treat percent as a count per hundred. Convert 15% to a multiplier before applying it to 240.

15% = 15/100 = 0.15
0.15 × 240 = 36
Check: 36 ÷ 240 × 100 = 15%

The denominator for a share is the whole. If a quantity is already a percentage, changes to that percentage also need a baseline; use the percentage-change tool for that question.

One relationship, three rearrangements

A part divided by its whole gives the fractional share. Multiplying by one hundred expresses that same share as a percent. Rearrange the relationship to calculate an unknown part or an unknown whole.

A percent can exceed 100 when the part exceeds the comparison whole. Negative inputs are allowed for signed mathematical quantities; interpreting a negative whole as a population or a physical total requires care.

part = percent × whole / 100
percent = 100 × part / whole
whole = 100 × part / percent

Input limits and common mistakes

A whole of zero cannot be the denominator of a percentage, and a zero percent cannot determine a unique whole from a part. The tool rejects those divisions rather than inventing a result.

Use finite numbers with absolute value at most 1e100. Results use floating-point arithmetic and up to 12 significant displayed digits. Enter 15 for 15%, not 0.15, in a percent position.

Questions about percentage calculator

How do I find what percent 36 is of 240?

Choose “A is what percent of B?”, enter A = 36 and B = 240. The result is 15%.

How do I find the original whole?

Choose the third question. If 36 is 15% of a whole, use 36 × 100 / 15 = 240.

Can percentages be greater than 100?

Yes. For example, 300 is 150% of 200. This indicates a comparison quantity larger than the chosen whole.

Sources and verification

These references explain the formulas or formats. The worked examples above were created for this tool and checked against independent calculations or format round trips. AI-assisted development does not imply a named human expert review.

Published 2026-10-23. Examples are illustrations, not measurements of a service or claims about search rankings.

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Further reading

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