Percentage Difference Calculator

Compare two values and calculate their percentage difference relative to their average.

Calculate percentage difference

Enter two non-negative values. Neither value is treated as the starting value.

Compare two non-negative values symmetrically using their average as the reference.

What is percentage difference?

Percentage difference compares two values without declaring either one to be the original. It measures their absolute separation relative to their average.

Formula

|A − B| ÷ ((A + B) ÷ 2) × 100.

Worked example

For 80 and 100, the absolute difference is 20 and the average is 90, so the percentage difference is about 22.22%.

Why percentage difference is symmetric

Swapping A and B does not change the absolute difference or their average, so A versus B gives the same percentage difference as B versus A.

Zero values

If one value is zero and the other is positive, the percentage difference is 200%. Two zero values are undefined because their average is zero.

Percentage difference vs percentage change

Percentage difference is symmetric. Percentage Change Calculator is directional and divides by an original value. For basic percentage questions, use the Percentage Calculator.