Percentage Difference Calculator

Calculate the percentage difference between two values using the mean as the reference point.

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Percentage difference

40%

The percentage difference between 100 and 150 is 40%

Absolute difference
50
Average
125
Value 1
100
Value 2
150

How to use this result

Percentage difference measures how far apart two values are relative to their average. Unlike percent change, the order of the values does not matter — the result is always the same. Use it when neither value is a clear baseline or reference point.

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Percentage Tools

Percentage difference calculator: compare two values symmetrically

A percentage difference calculator measures how far apart two values are relative to their average. Unlike percent change, which uses one value as the reference, percentage difference treats both values equally. This makes it the right tool when comparing two measurements, prices, or data points without implying that one came before the other.

The percentage difference formula

Percentage difference divides the absolute difference between two values by the average of those values, then multiplies by 100. Because it uses the mean as the denominator, the result is the same regardless of which value is listed first.

For example, comparing a price of 80 and a price of 100: the absolute difference is 20, the average is 90, and the percentage difference is 20 / 90 x 100, which is approximately 22.2%.

Percentage difference = (|A - B| / ((A + B) / 2)) x 100

The absolute difference divided by the mean of the two values, expressed as a percentage.

When to use percentage difference vs. percent change

Use percent change when one value is clearly the starting point and the other is the ending point (before/after, old/new). Use percentage difference when neither value has priority, such as comparing two products, two measurements taken under different conditions, or two estimates from different sources.

In scientific contexts, percentage difference is often used to compare an experimental result with a theoretical prediction when neither is clearly the reference. In contrast, percent error specifically uses the theoretical value as the reference.

Frequently asked questions

Is percentage difference always positive?

Yes. The formula uses the absolute value of the difference, so the result is always zero or positive. A percentage difference of zero means the two values are identical.

 Can percentage difference exceed 200%?

The maximum percentage difference approaches 200% when one value is very large and the other is very close to zero. It cannot exceed 200% because the average of the two values is always at least half the larger value.

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