Percentage Difference Calculator
Find the percentage difference between two values — useful when comparing two numbers with no clear "before" and "after."
Enter two values to compare
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Percentage difference between the two values
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Value A
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Average
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Abs. difference
Frequently asked questions
What is the percentage difference formula? ›
Percentage Difference = (|A − B| ÷ ((A + B) / 2)) × 100. It uses the average of the two values as the reference point, so it's symmetric — swapping A and B gives the same result. Example: A = 80, B = 100 → |80−100| ÷ ((80+100)/2) × 100 = 20 ÷ 90 × 100 ≈ 22.22%.
When should I use percentage difference vs percentage change? ›
Use percentage difference when comparing two values as equals — like two prices, two test scores, or two measurements — where neither is the clear "original." Use percentage change when one value comes before the other in time or is the baseline.
Why is the result different from percentage change? ›
Because they use different reference values. Percentage change uses the original value as the denominator; percentage difference uses the average. For 80 vs 100: percentage change from 80 to 100 = 25%, but percentage difference = 22.22%.
About this calculator
Percentage difference is useful in science, business, and everyday comparisons when you want to describe how far apart two numbers are as a percentage of their average. Unlike percentage change, it doesn't assume one number is the "starting point."