Formula
The difference is divided by the average of the absolute values:
Percentage difference = |first − second| / ((|first| + |second|) / 2)
The result is never negative. Direction belongs on the percent-change page.
Assumptions
- Neither number is preferred as the base.
- Both values cannot be zero.
Worked example
40 and 60 have a percentage difference of 40.00%.
Input definitions
- First and second value
- The two numbers being compared. Order does not change the result.
Limitations
Results are rounded for display. This is a classroom calculation, not a measurement from a lab or a financial filing.
Questions
Why is 40 and 60 not a 50% change?
A change from 40 to 60 divides by 40. This page divides by their average, 50.
Can the result be negative?
No. The absolute difference removes the direction.