Percentage Difference Calculator

Find how much two values differ in percentage terms. Ideal for comparing results, prices, or performance metrics.

Compare two values and find their percentage difference

Quick Answer

Percentage change compares a newer value to an older starting point. Percentage difference compares two values relative to their average, without a specific 'start' or 'end'. This makes it ideal for comparing two independent items, like Product A vs Product B.

Percentage Difference Calculator

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How to Calculate Percentage Difference

Enter the two values you want to compare.
Click Calculate to see their percentage difference with steps.

Formula:

Percentage Difference = (|A − B| ÷ ((A + B) ÷ 2)) × 100

What Is Percentage Difference?

Percentage difference shows the relative gap between two values based on their average, not on a single starting point. It’s common in science, data analysis, and economics where you want a fair, symmetric comparison.

Formula

(|A − B| ÷ ((A + B) ÷ 2)) × 100

Need a directional change from an original value instead? Try the Percentage Change Calculator.

Step-by-Step Worked Example

Example: compare 48 and 57.6.

Absolute difference: |57.6 − 48| = 9.6
Average: (57.6 + 48) ÷ 2 = 52.8
Percent difference: 9.6 ÷ 52.8 × 100 = 18.18%

For old→new comparisons instead, see the Percent Increase or Percent Decrease tools.

Excel & Google Sheets Method

You can compute percent difference quickly in a spreadsheet:

Formula: =ABS(B2-A2)/((A2+B2)/2) then format as %.

Safe version: =IF((A2+B2)=0,"",ABS(B2-A2)/((A2+B2)/2))

Common Mistakes to Avoid

Using percentage change when you actually need a symmetric comparison.
Forgetting the absolute value in the numerator.
Dividing by a single value instead of the average of both.
Not handling the zero-average case (result is undefined).

Common Examples

Compare 100 vs 120

Result: 18.18% difference

Compare 80 vs 100

Result: 22.22% difference

Prices: $2.40 vs $2.52

Result: 4.92% difference

Scores: 72 vs 90

Result: 22.22% difference

Negatives: −40 vs −50

Result: 22.22% difference (relative to their average)

Frequently Asked Questions

What is percentage difference?

It measures how much two values differ as a percentage of their average. It’s symmetric, so swapping A and B gives the same result.

How is percentage difference different from percentage change?

Percentage change compares a new value to an original baseline (direction matters). Percentage difference compares two values relative to their average and is not directional.

What’s the formula for percent difference?

Percent Difference = (|A − B| ÷ ((A + B) ÷ 2)) × 100.

Can I use negative numbers?

Yes. The absolute difference handles sign, and the average sets the scale. If the average is 0 (e.g., +x and −x), the result is undefined.

How do I calculate percentage difference in Excel or Sheets?

Use =ABS(A2-B2)/((A2+B2)/2) and format as %. Wrap with IF for safety: =IF((A2+B2)=0, "", ABS(A2-B2)/((A2+B2)/2)).

When should I use percent difference vs percent change?

Use percent difference to compare two independent values (prices at two stores, two measurements). Use percent change to measure movement from a specific starting value.