Percentage Difference Calculator

How it works

Percent difference = |A − B| ÷ ((A + B) ÷ 2) × 100. The average of A and B sits in the denominator, which is why the result is symmetric. Use percentage change (not difference) when one value is clearly the "original".

Frequently asked

What is the difference between percentage difference and percentage change?

Percentage difference is symmetric — it compares two values without one being the baseline. Percentage change is directional — it measures how much something moved from an original value.

When should I use percentage difference?

When comparing two measurements of the same kind where neither is the "before" — e.g., two different sensor readings, two prices in different stores, two test scores.

Can the percent difference be more than 100%?

Yes. If A = 10 and B = 100, the difference is 90 ÷ 55 × 100 ≈ 164%. It happens whenever the two values are very far apart.