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Percentage Calculator

Work out a percentage of a value, express one number as a percentage of another, or calculate percentage change.

Details

Your Results

What Percentage Calculator does

Most percentage confusion comes from asking the wrong one of three questions. What is 20% of 80? 20 is what percent of 80? What is the change from 20 to 80?

Each is a different calculation, and this tool separates them so the right one is used.

  • X percent of Y
  • X as a percentage of Y
  • Percentage change from one value to another

How to use Percentage Calculator

  1. 1

    Choose the question

    Pick the mode that matches what you are actually asking.

  2. 2

    Enter the two numbers

    The result updates as you type.

Example

The same two numbers, three questions

Input

20 and 80

Output

20% of 80          = 16
20 is what % of 80 = 25%
Change 20 → 80     = +300%

Limits and known behaviour

  • A percentage increase followed by the same percentage decrease does not return to the original value. Add 10% to 100 and you get 110; take 10% off 110 and you get 99.
  • Percentage change is undefined when the starting value is zero, since there is nothing to compare against.
  • Percentages of negative numbers are arithmetically valid but frequently misleading in a report; state the base explicitly.
  • Percentage points and percentages are different units: moving from 10% to 12% is a rise of 2 percentage points, or of 20%.

Privacy and data handling

Runs entirely in your browser

  • The calculation runs in this page. Nothing you enter is transmitted or stored.
  • The tool works offline once the page has loaded.

Site-wide data handling, including analytics and advertising, is described in the privacy policy.

Frequently asked questions

Why does a 50% loss need a 100% gain to recover?

Because the base changes. Losing half of 100 leaves 50, and getting back to 100 from 50 means doubling, which is a 100% gain. Percentages are always relative to what they are calculated from.

What is the difference between percent and percentage points?

A rate moving from 10% to 12% has risen 2 percentage points, and also risen 20% relative to where it was. Mixing the two is a common source of misleading statistics.