Percentage Difference Calculator
Work out the percentage difference between two numbers.
Percentage difference
40%
- Absolute difference
- 20
- Average of the two
- 50
v1.0 · Reviewed September 2026
How this is worked out
The absolute difference between the two values is divided by their average, then expressed as a percentage.
Worked example
- 40 and 60
|40 − 60| = 20, average 50, so 20 ÷ 50
40%
Assumptions and limits
- Percentage difference is symmetric and uses the average as the base. Percentage change is different: going from 40 to 60 is a 50% increase, while going from 60 to 40 is a 33.33% decrease.
- Always positive, because the difference is taken as an absolute value.
- If the two values average zero the calculation is undefined and no result is shown.