What is the Percentage Difference Calculator?
Percentage difference compares two numbers when neither is the original. It divides the gap by their average, so the order of the values does not matter.
How to use the Percentage Difference tool
- Enter First value and Second value.
- The result updates instantly as you type, or press Calculate.
- Use Try an example to see how it works, and Reset to start again.
Formula
Percentage difference = |A − B| ÷ ((A + B) ÷ 2) × 100.
Worked example
With first value 40, second value 60, the percentage difference comes to 40%. Absolute difference: 20; Average of the two: 50.
Frequently asked questions
How is it different from percentage change?
Percentage change uses the starting value as the base. Percentage difference uses the average of both, so it is symmetric.
When should I use it?
Use it to compare two measurements or results where neither is a reference point.
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Checked by Calcovate · Formula tested against worked examples · Updated 7 Nov 2026 · How we check our calculators.