Calculate a percentage

Answer common percentage questions: a percent of a number, a ratio as a percent, change, or the base represented by a percent.

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ToolPercentage Calculator
Input
Output
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Preview

How it works

The selected mode applies one of four identities: percentage of a number, what percent one number is of another, percentage change, or the number represented by a percentage. Percent signs and the word “of” are removed before two operands are parsed.

  • The “what is A% of B” mode is initial because it is a direct percentage question.
  • Zero denominators are rejected in modes that divide by them.

Worked example

Calculate Percentage
Calculate 15% of 250
Input
											15 of 250
Output
												15% of 250 = 37.5

When to use this

Discounts find a fraction of list price, reports express one count as a share of another, and target-setting solves a base from a percentage.

Edge cases

  • A percentage of zero is valid and returns zero, while asking what percent 5 is of 0 has no finite answer.
  • A negative base preserves signed arithmetic and is not made absolute in every mode.
  • The parser accepts “20% of 80” only in the mode expecting that two-part form.