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Percentage Difference Calculator

Find the percentage difference between any two numbers, with a signed difference and the average they are measured against.

Percentage Difference

Enter two values. Results update live.

Result
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Enter numbers to see the result.

Absolute diff.
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Percent change
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Average
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Formula: Percentage difference = (|A - B| / ((A + B) / 2)) x 100. It is symmetric, so the order of the values does not matter.
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A symmetric comparison

Percentage difference divides the absolute gap between two values by their average, not by either value alone. That makes it symmetric: comparing 80 and 100 gives the same answer either way round, which is exactly what you want when neither value is the obvious baseline.

Difference vs change

Percentage difference and percent change are not the same. Percent change measures against the old value, so it is directional. Percentage difference measures against the average, so it answers how far apart two values are, not how much one grew into the other.

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Percentage Difference FAQs

What is the percentage difference between 80 and 100?
The difference is |100 - 80| / ((80 + 100) / 2) x 100 = 22.22%. The tool above computes this instantly, with the signed difference and the average shown as well.
When should I use percentage difference instead of percent change?
Use percentage difference when neither value is a baseline, for example comparing two prices, two test scores, or results from two labs. Use percent change when one value is clearly the old or original one.
Is percentage difference the same forwards and backwards?
Yes. Because it divides by the average of the two values, swapping A and B gives the identical result. Percent change does not have this property.
Can percentage difference exceed 100%?
Yes. If one value is more than three times the other, the difference exceeds 100%. For example 10 and 100 differ by about 163.64%.
Is my data sent to a server?
No. All calculations run in your browser with JavaScript, so your numbers never leave your device.
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