Percent Difference Calculator
Percent difference compares two values when neither one is the “original”. Enter the two numbers in either order: the gap between them is divided by their average, so the answer is the same both ways.
- Absolute difference
- 10
- Average of the two
- 45
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Formula
How to use it
- Enter the first value.
- Enter the second value — the order does not matter.
- Read the percent difference, along with the absolute difference and the average used as the base.
Worked examples
Two quotes of 40 and 50
- Percent difference
- 22.22%
- Absolute difference
- 10
- Average of the two
- 45
Readings of 120 and 100
- Percent difference
- 18.18%
- Absolute difference
- 20
- Average of the two
- 110
When to use it instead of percent change
Use percent difference to compare two things of the same kind measured at the same time: two price quotes, two lab readings, the heights of two buildings. Use percent change when one value came first and the other replaced it.
For 40 and 50 the percent difference is 22.22%. Percent change would give +25% going from 40 to 50 and −20% going from 50 to 40 — two different answers for the same pair of numbers.
The largest possible answer
Because the base is the average of the two values, percent difference tops out at 200%, reached when one of the values is zero. Values of 10 and 90 differ by 160%.
Questions people ask
What is the percent difference between 40 and 50?
22.22%. The difference is 10 and the average is 45, and 10 ÷ 45 = 0.2222.
What is the percent difference between 120 and 100?
18.18%. The difference is 20 and the average is 110.
Can percent difference be more than 100%?
Yes. It can be anything from 0% up to 200%. For example 10 and 90 have a percent difference of 160%.