Percent difference calculator
Use it to compare two values of equal standing, such as two store prices or two measurements. The order does not matter.
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How to use it
- Enter value a and value b.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Percent difference = (|A - B| ÷ ((A + B) ÷ 2)) × 100
Example
Inputs: Value A = 10, Value B = 20. Result: Percent difference: 66.67%; Absolute difference: 10; Average: 15.
Limits and caveats
- This is not percent change. If you have an old and a new value, use the percent change calculator.
- Designed for non-negative values; the measure has no clear meaning for negative numbers.
Questions about this tool
When should I use percent difference instead of percent change?
When neither value is the reference, such as the price of one product in two different stores.
What is the percent difference between 10 and 20?
The difference is 10 and the average is 15, so the percent difference is about 66.67%.
Does swapping the two values change the answer?
No. The formula uses the absolute difference and the average of both values.