Percentage difference calculator
Compare two numbers and express the gap between them as a percentage — without treating either one as the starting point.
Percentage difference calculator
Example: compare 80 and 100
Enter values to see the result
What is percentage difference?
Percentage difference compares two values by expressing their absolute difference as a percentage of their average. It has no direction — swapping the values gives the same result.
Use it when comparing two equivalent things: two quotes, two measurements, two test results. There is no “original” and no “new.”
Formula
|A − B| ÷ ((|A| + |B|) ÷ 2) × 100
Examples
Two supplier quotes
$840 vs $960
≈ 13.33%
Lab measurements
4.85 vs 5.10
≈ 5.03%
Exam scores
72 vs 88
20%
Fuel economy
38 mpg vs 44 mpg
≈ 14.63%
Frequently asked questions
What is the difference from percentage change?
Percentage change has direction and needs a starting point. Use percentage change for before/after; use percentage difference for two equivalent values.
Can the result be negative?
No. The formula uses absolute value, so the result is always zero or positive.
What does 0% mean?
The two values are identical.
When should I avoid it?
When one value is clearly the original and the other is the result of a change — use percentage change instead.
Is it the same as relative error?
Similar but not identical. Relative error divides by the reference value; percentage difference divides by the average of both.