Percentage difference calculator

How far apart are two numbers, relative to their average?

Formula Percentages

Percentage difference

Absolute difference: 20
Average: 50

How it works

Percentage difference is used when neither value is the reference, for example two quotes or two measurements. Take the absolute gap between them and divide it by their average.

Because the base is the average, swapping A and B gives the same answer. That is the main difference from percentage change, which uses the old value as the base.

Formula

% difference = |A − B| ÷ ((A + B) ÷ 2) × 100

Worked example

For 40 and 60 the gap is 20 and the average is 50, so the percentage difference is 20 ÷ 50 × 100 = 40%.

Questions people ask

Why is the answer not 50% for 40 and 60?

50% is the increase from 40 to 60, measured from 40. The percentage difference measures from the average, 50, which gives 40%.

Can the percentage difference exceed 100%?

Yes, up to 200%, which happens when one of the two values is zero.