How this calculation works
Percentage difference compares two measurements without declaring either one the starting point. It divides the absolute gap by the average magnitude. Swapping the inputs therefore leaves the answer unchanged. For growth, decline or a price change over time, use percentage change instead.
Difference = |A − B|. Percentage difference = |A − B| ÷ [(|A| + |B|) ÷ 2] × 100. When both values are zero, this tool reports zero difference.
Worked example
This example uses illustrative inputs. Your current result is shown above.
For A = 100 and B = 125, the gap is 25 and the average magnitude is 112.5. Percentage difference = 25 ÷ 112.5 × 100 ≈ 22.222222%.
Assumptions and limits
- The inputs must measure the same quantity in the same unit.
- Absolute magnitudes are used in the denominator, including for negative inputs.
- This symmetric comparison has no increase/decrease direction and is not percentage error relative to a known true value.
Questions people ask
Which value should I enter first?
Either. The absolute gap and average magnitude are unchanged when A and B are swapped.
Why is this different from percentage change?
Percentage change uses a chosen original value as the denominator. Percentage difference uses the average magnitude of both values and does not designate a baseline.