How It Works
Percentage difference expresses the absolute difference between two numbers relative to their average. It is symmetric: swapping inputs yields the same result.
Percent difference = (|A − B| ÷ ((|A| + |B|) ÷ 2)) × 100
Using absolute values for the denominator keeps the measure meaningful if values can be negative. If both values are zero the result is undefined (division by zero).
Interpretation
Near 0% means the numbers are similar. Larger percentages indicate a greater relative difference—suitable for comparing populations, prices, or any pair of quantities.