Percentage Difference Calculator

Enter two numbers to see how far apart they are, as a percentage of their average. The order does not matter. The working is shown, and everything runs in your browser.

First value

Second value

Percentage difference

22.22%

80 and 100 differ by 20, which is 22.22% of their average (90).

Difference: 20
Average of the two: 90
Change from 80 to 100: +25%

Show working

|80 − 100| = 20
(80 + 100) ÷ 2 = 90
20 ÷ 90 × 100 = 22.22%

Calculated instantly in your browser with standard formulas. Double-check anything important. Full disclaimer and terms of use.

What percentage difference means

Percentage difference tells you how far apart two numbers are, compared with their average. It treats both numbers equally, so swapping them gives the same answer. That makes it the right tool when you compare two things, such as two prices or two measurements, and neither is the "before" or the "after".

The formula

Percentage difference = |A − B| ÷ ((A + B) ÷ 2) × 100
Example with 80 and 100: the gap is 20, the average is 90, and 20 ÷ 90 × 100 = 22.22%.

Percentage difference versus percentage change

	Percentage difference	Percentage change
Compares	Two equal values	An old value and a new one
Divides by	The average of the two	The old value
Order matters?	No	Yes
80 and 100	22.22%	+25% (80 to 100), −20% (100 to 80)

When to use it

Comparing the prices of the same item at two shops.
Checking how far an experiment's result is from a second measurement.
Comparing two groups, for example the test scores of two classes.
Use percentage change instead when you are tracking one thing over time, such as a price rising from last month.

How to calculate percentage difference in Excel or Google Sheets

With the two numbers in A1 and B1, use =ABS(A1-B1)/AVERAGE(A1,B1) and format the cell as Percentage.

How to use the Percentage Difference Calculator tool

Type the first and second value.
Read the percentage difference in large type.
Compare the two bars to see how close the values are, and open "Show working" for the steps.
Use the swap button to check that the answer is the same the other way round.

Frequently asked questions

How do I calculate percentage difference?

Subtract one number from the other and ignore the sign, divide by the average of the two numbers, then multiply by 100. For 80 and 100: 20 ÷ 90 × 100 = 22.22%.

What is the difference between percentage difference and percentage change?

Percentage change compares a new value with an old one, so it depends on which is the starting point. Percentage difference compares two values with no starting point, using their average, so it gives the same answer in either order. From 80 to 100 is a 25% change, but the difference between 80 and 100 is 22.22%.

When should I use percentage difference?

Use it to compare two things that are equals, such as the prices at two shops, the results of two tests or two measurements, where neither is the "original".

Why can the answer be over 100%?

When one number is more than three times the other, the gap is bigger than their average. 10 and 100 differ by 90, and their average is 55, so the percentage difference is about 163.6%.

Guides

How to Calculate Percentages: Percent Of, Increase and Decrease