How this calculator works
Find the absolute gap between the values and divide it by their arithmetic mean. Switching the two values leaves the answer unchanged. The conventional interpretation uses positive values. This calculator also accepts negatives and retains the sign of the mean in the denominator.
Formula
Difference (%) = |a - b| / ((a + b)/2) × 100. The mean must be non-zero.
Worked example
For 10 and 15, the gap is 5 and the mean is 12.5, so the difference is 40%. For 100 and 110, it is about 9.52381%.
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Frequently asked questions
How is this different from percentage change?
Percentage change chooses a starting value as the reference. Percentage difference treats the pair equally and uses their mean.
What happens with negative values?
The numerator is non-negative, but a negative mean gives a negative result under this formula. Opposite values with a zero mean are rejected.
Can the difference exceed 100%?
Yes. When one value is negative, the gap can be more than twice the mean; for -5 and 15 the result is 400%.