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Enter two values
Use the A and B fields for peer measurements, scores, or experimental results.
Free Percent Difference Calculator
A percent difference calculator measures the symmetric difference between two values as a percentage of their average magnitude. Enter any two numbers to see the formula, substituted values, and clear calculation steps.
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Symmetric comparison
Enter two values
Whole numbers, decimals, negative values, and scientific notation are supported. The order does not change the result.
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Percent difference result
Symmetric difference
Enter both values to calculate their percent difference.
Absolute difference
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Average magnitude
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Formula
|A - B| ÷ ((|A| + |B|) ÷ 2) × 100
Step-by-step work
The substituted values and calculation steps will appear after both inputs are valid.
How to Calculate Percent Difference
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Find the average magnitude
Average the absolute values so negative inputs keep a meaningful denominator.
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Read the percentage
Divide the absolute difference by that average and multiply by 100.
Percent Difference vs Percent Change
Percent difference
Use percent difference when the two values are peers and neither is a baseline. The formula is symmetric, so reversing A and B does not change the result.
Percent change
Use percent change when one value is the original baseline and the other is new. Its direction matters because the original value is the denominator.
Percent Difference Calculator FAQ
What is a percent difference calculator?
A percent difference calculator compares two values without treating either one as the original. It divides their absolute difference by their average magnitude and multiplies by 100.
What is the formula for percent difference?
Percent difference is |A - B| divided by ((|A| + |B|) / 2), multiplied by 100. Absolute values keep the denominator non-negative.
What is the difference between percent difference and percent change?
Percent difference is symmetric and compares two peer values. Percent change is directional and measures change from a specific original value to a new value.
Can percent difference be greater than 100%?
Yes. Percent difference can exceed 100% when the gap between two values is large compared with their average magnitude. With this symmetric formula, the result is at most 200%.
What happens when both values are zero?
Two zero values are identical, so this calculator reports a 0% difference instead of attempting to divide zero by zero.