Percentage Difference Calculator

The percentage difference calculator finds how different two values are relative to their average. Unlike percentage change, percentage difference treats both values equally — there's no 'starting' value or defined direction. This makes it ideal for comparing two measurements, prices, or quantities where neither is the baseline. The result is always positive and symmetric, meaning swapping which value is entered first produces the exact same answer. Use it when both values have equal standing — such as comparing two prices, two test scores, or two experimental readings — rather than when one value is clearly a 'before' and the other is an 'after'. Common applications include comparing competing product prices, evaluating two job salary offers, benchmarking a business metric against an industry average, or assessing the variance between two independent measurements of the same physical quantity in a laboratory or quality control setting. The calculator also returns the absolute difference and the average of the two values, giving you full context for interpreting the percentage result.

Percentage difference is calculated using the formula: |A − B| ÷ ((A + B) / 2) × 100. First, the absolute difference between the two values is found by subtracting one from the other and removing any negative sign. That difference is then divided by the average (midpoint) of the two values, which serves as a neutral reference point. Multiplying by 100 expresses the result as a percentage. Because both the numerator and denominator treat A and B symmetrically, swapping which value is A and which is B always produces the same result — a key distinction from percent change.