Percentage Difference Calculator
Compare two numbers when neither is the starting point. Get the percentage difference, the average it's measured against, and the formula with your values.
Examples
46.15%
Absolute difference
30
Average (reference)
65
Formula With Your Numbers
|50 − 80| ÷ ((50 + 80) ÷ 2) × 100 = 46.15%Compared With Percentage Change
From A to B: +60%. From B to A: −37.5%. Percentage change depends on which number you start from. Percentage difference treats both equally, so it is 46.15% either way.
Percentage difference measures how far apart two numbers are relative to their average. Use it when neither value is the "original" — comparing the price of the same item at two stores, two lab measurements, or the populations of two towns — instead of percentage change, which needs a starting point. This calculator takes any two non-negative numbers and returns the percentage difference, the absolute difference, and the average used as the reference, then shows how the result compares with percentage change in each direction. Because the formula divides by the average, swapping the two numbers always gives the same answer.
How to Use the Percentage Difference Calculator
1. Enter the two numbers
Type the values you want to compare into the first and second boxes. The order doesn't matter.
2. Read the percentage difference
The result shows the percentage difference, the absolute difference between the numbers, and the average used as the reference.
3. Check the comparison panel
If you're not sure which measure fits, the comparison shows percentage change from A to B and from B to A, which treat one number as the starting point.
4. Copy the result
Use the copy button to grab the percentage for a report, spreadsheet, or assignment.
Percentage Difference Formula
Percentage difference
Percentage Difference = |A − B| ÷ ((A + B) ÷ 2) × 100Example: for 50 and 80, |50 − 80| = 30 and the average is 65, so 30 ÷ 65 × 100 = 46.15%.
Percentage change (for comparison)
Percentage Change = (New − Original) ÷ Original × 100Going from 50 to 80 is +60%, and going from 80 to 50 is −37.5%. Percentage difference gives 46.15% in both directions.
In Excel or Google Sheets
=ABS(A1-B1)/AVERAGE(A1,B1)Put your two numbers in A1 and B1, enter the formula in another cell, and format that cell as a percentage.
How to Calculate Percentage Difference Between Two Numbers
Take two numbers, 50 and 80. Here is the full calculation, one step at a time.
- 1
Find the absolute difference
|50 − 80| = 30Subtract the smaller number from the larger one so the result is positive.
- 2
Find the average of the two numbers
(50 + 80) ÷ 2 = 65Add them and divide by 2. This is the reference the gap is measured against.
- 3
Divide the difference by the average
30 ÷ 65 = 0.4615This gives the difference as a decimal fraction of the average.
- 4
Multiply by 100
0.4615 × 100 = 46.15%That's the percentage difference.
Percentage Difference Examples
| A | B | Difference | Average | Percentage difference |
|---|---|---|---|---|
| 50 | 80 | 30 | 65 | 46.15% |
| 100 | 120 | 20 | 110 | 18.18% |
| 20 | 30 | 10 | 25 | 40% |
| 8 | 12 | 4 | 10 | 40% |
| 1,000 | 1,500 | 500 | 1,250 | 40% |
| 45 | 55 | 10 | 50 | 20% |
Percentage Difference vs Percentage Change
The two measures answer different questions. Percentage change asks how much a value moved from a starting point, so the answer depends on direction. Percentage difference asks how far apart two values are, with no starting point, so the answer is the same in both directions.
| A | B | Change A to B | Change B to A | Percentage difference |
|---|---|---|---|---|
| 50 | 80 | +60% | −37.5% | 46.15% |
| 100 | 120 | +20% | −16.67% | 18.18% |
| 20 | 30 | +50% | −33.33% | 40% |
| 40 | 60 | +50% | −33.33% | 40% |
If one value is clearly the original, such as last year's sales compared with this year's, use the percentage increase calculator or the percentage decrease calculator instead.
Percentage Difference in Excel and Google Sheets
Put your two numbers in cells A1 and B1, then enter this formula in a third cell and format it as a percentage:
=ABS(A1-B1)/AVERAGE(A1,B1)ABS removes the sign so the order of the numbers doesn't matter, and AVERAGE supplies the reference value. With 50 and 80 it returns 46.15%, matching the calculator above.
When to Use Percentage Difference
- Comparing the price of the same item at two different stores.
- Comparing two measurements of the same quantity, such as results from two lab runs or two instruments.
- Comparing two groups of similar standing, like the populations of two towns or the scores of two classes.
- Any comparison where it would be arbitrary to call one number the starting point.
Frequently Asked Questions
What is percentage difference?
Percentage difference is the gap between two numbers expressed as a percentage of their average. It's used when neither number is the original or reference value, so the comparison is symmetric.
How do you calculate the percentage difference between two numbers?
Subtract the smaller from the larger to get the absolute difference, add the two numbers and divide by 2 to get their average, divide the difference by the average, then multiply by 100. For 50 and 80: 30 ÷ 65 × 100 = 46.15%.
What is the difference between percentage difference and percentage change?
Percentage change measures how much a value moved from a starting point, so it depends on direction: 50 to 80 is +60%, but 80 to 50 is −37.5%. Percentage difference compares two values with no starting point and always gives the same answer, 46.15% in this case.
Does the order of the numbers matter?
No. The formula uses the absolute difference and the average of both numbers, so swapping them never changes the result.
Can percentage difference be more than 100%?
Yes. For non-negative numbers it reaches a maximum of 200%, which happens when one number is zero. For example, comparing 0 and 40 gives 40 ÷ 20 × 100 = 200%.
How do I calculate percentage difference in Excel or Google Sheets?
With your numbers in A1 and B1, enter =ABS(A1-B1)/AVERAGE(A1,B1) in another cell and format it as a percentage. The ABS function removes the sign so the order of the numbers doesn't matter.
How do I find the difference between two percentages?
There are two ways to read it. The raw gap, such as 20% to 30%, is 10 percentage points. The relative gap is the percentage difference between 20 and 30, which is 40%. Say which one you mean when reporting results.
Why divide by the average instead of one of the numbers?
Using the average treats both numbers equally. If you divided by just one of them, the answer would change depending on which you picked, which defeats the purpose when there's no original value.
Why does the calculator reject negative numbers?
Percentage difference is defined for non-negative quantities such as prices, measurements, and counts. With mixed signs the average can be close to zero, which would make the percentage meaningless or very misleading.
Common Mistakes
❌ Using percentage change when there is no original value
Percentage change treats one number as the starting point, so swapping the two gives a different answer. If you're comparing two things side by side, percentage difference is the fair measure.
❌ Dividing by only one of the numbers
Dividing the gap by just A or just B gives a different result depending on which you pick. Percentage difference divides by the average of both so the answer is the same either way.
❌ Confusing percentage difference with percentage points
The gap between 20% and 30% is 10 percentage points, but the percentage difference between 20 and 30 is 40%. Percentage points are a raw subtraction; percentage difference is relative to the average.
❌ Expecting the result to stay under 100%
For non-negative numbers the percentage difference can reach 200%, which happens when one of the numbers is zero. A result above 100% is normal, not an error.
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