Overview
Relative difference compares two values regardless of their absolute size. For example, the difference between 100 and 120 is 20, and the relative difference is 18.18% because the average magnitude is 110.
Formula
Relative difference = (|a − b| ÷ ((|a| + |b|) ÷ 2)) × 100.
How it works
Enter the two values
They can be positive or negative.
Calculate the absolute difference
Subtract the values and take the absolute value.
Divide by the average magnitude
Then multiply by 100 to get the percentage.
Worked examples
Example 1: 100 and 120
The difference is 20, the average is 110, and the relative difference is 18.18%.
Example 2: 50 and 75
The difference is 25, the average is 62.5, and the relative difference is 40%.
Frequently asked questions
What is the difference between relative difference and percentage change?
Percentage change uses the original value as its base, while relative difference uses the average of the two values.
Can relative difference be negative?
Not in this calculator, because absolute values are used.
What if one value is zero?
The difference can be calculated unless both values are zero; the average will be half of the other value.
This calculator is for educational and informational purposes only and is not a substitute for professional advice.