Percentage Difference Calculator
Find the percentage difference between two numbers, see how it differs from percent change, or compare a value with a target. Every answer shows the steps. It runs in your browser, so nothing you enter is stored.
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Steps
Quick answer
Percentage difference tells you how far apart two numbers are, compared with their average. Subtract the smaller number from the larger one, divide by the average of the two numbers and multiply by 100. For example, 80 and 100 are 22.22 percent apart.
Use the calculator above for the three most common jobs: finding the percentage difference between two numbers, seeing it next to percent change, and comparing a value with a target. Neither number is treated as the starting point, so the order does not matter.
How to calculate percentage difference
Follow these four steps. Here two shops sell the same item for 40 and 60.
- Subtract the smaller number from the larger number. 60 minus 40 is 20.
- Add the two numbers and divide by 2 to get the average. 40 plus 60 is 100, and 100 divided by 2 is 50.
- Divide the difference by the average. 20 divided by 50 is 0.4.
- Multiply by 100 to turn it into a percent. 0.4 times 100 is 40, so the two prices are 40 percent apart.
You always divide by the average, never by one of the two numbers. That is what makes the answer the same whichever number you type first.
Percentage difference formulas
| What you want | Formula |
|---|---|
| Percentage difference between a and b | |a – b| / ((a + b) / 2) x 100 |
| Plain difference | |a – b| |
| Average of two numbers | (a + b) / 2 |
| Percent change from a to b | (b – a) / |a| x 100 |
| Difference from a reference value | (value – reference) / |reference| x 100 |
The bars around a minus b mean absolute value. You ignore the sign and keep only the size of the gap. Percentage difference is never negative, but percent change and the reference formula can be.
Percentage difference examples
| Situation | Value 1 | Value 2 | Difference | Percent difference |
|---|---|---|---|---|
| Prices in two shops | 80 | 100 | 20 | 22.22% |
| Test scores of two students | 72 | 90 | 18 | 22.22% |
| Two phone plans | 25 | 40 | 15 | 46.15% |
| Heights of two people (cm) | 170 | 180 | 10 | 5.71% |
| Weights of two parcels (kg) | 62 | 68 | 6 | 9.23% |
| Salaries of two jobs | 50,000 | 60,000 | 10,000 | 18.18% |
The same gap can look small or large. The gap between 170 and 180 is 10, and so is the gap between 20 and 30. The first is 5.71 percent and the second is 40 percent. The average sets the scale, so a gap matters more when the numbers are small.
Percentage difference vs percent change
These two are often mixed up. Percent change has a clear start and end, like a price going from 80 to 100. Percentage difference has no start and no end. It compares two values that matter equally, like the prices in two different shops.
| Measure | Divides by | 80 and 100 | 100 and 80 |
|---|---|---|---|
| Percentage difference | The average | 22.22% | 22.22% |
| Percent change | The first number | 25% increase | 20% decrease |
Use percentage difference when neither number is more important, such as comparing two products, two groups or two measurements. Use percent change when one number came first and the other came later. For those cases try our percentage increase calculator and percentage decrease calculator.
Comparing a value with a target
Sometimes one number is the correct or expected value, such as a lab result against the accepted value, or actual spending against a budget. Then you divide by that reference number instead of the average, because it is the number you are measuring against.
Here a lab measures 98 and the accepted value is 100. The difference is 2, and 2 divided by 100 is 0.02, so the result is 2 percent below the target. The answer changes if you swap the two numbers, because the reference is the base. This is the same idea as percent error in science classes.
Percentage difference in Excel and Google Sheets
Put the two numbers in cells A1 and B1, then type this formula in cell C1.
Format cell C1 as a percentage. Excel and Sheets multiply by 100 for you, so you do not add it to the formula. In Google Sheets, choose Format, then Number, then Percent. To get percent change instead, use =(B1-A1)/ABS(A1).
Special cases
Same numbers. The difference is 0, so the percentage difference is 0 percent.
One number is 0. The answer is always 200 percent, as long as the other number is not 0. For 0 and 50 the gap is 50 and the average is 25, and 50 divided by 25 is 2.
Numbers that cancel out. For -5 and 5 the average is 0, so the formula would divide by 0. The calculator tells you when this happens.
Negative numbers. The formula still runs, but the answer is hard to read. This calculator divides by the size of the average, so read the result with care.
Large gaps. For two positive numbers the answer can never be more than 200 percent.
Common mistakes
Dividing by one number instead of the average. That gives percent change, not percentage difference.
Using it when there is a start and an end. A price that moves from 80 to 100 is a 25 percent increase, not a 22.22 percent difference.
Forgetting to multiply by 100. That leaves a decimal such as 0.2222 instead of 22.22 percent.
Mixing it up with percentage points. If a rate moves from 10 percent to 12 percent, that is 2 percentage points. Use our percentage point calculator for that.
About this calculator
The calculator uses the standard formula shown above and rounds results to four decimal places at most. It works with whole numbers and decimals, accepts commas in large numbers, and runs in your browser, so nothing you enter is stored or sent.
Frequently asked questions
How do I calculate percentage difference?
Subtract the smaller number from the larger one, divide the result by the average of the two numbers, then multiply by 100. For 40 and 60 the difference is 20, the average is 50, 20 divided by 50 is 0.4, and 0.4 times 100 is 40. The two numbers are 40 percent apart.
What is the percentage difference formula?
Percentage difference = |value 1 – value 2| / ((value 1 + value 2) / 2) x 100. The bars mean you ignore the sign of the gap and keep only its size. The bottom of the fraction is the average of the two values.
What is the difference between percentage difference and percent change?
Percent change measures movement from a starting value to a new value, so it divides by the starting value and can be positive or negative. Percentage difference compares two values that have no order, so it divides by their average and is never negative. From 80 to 100 the percent change is 25 percent, and the percentage difference is 22.22 percent.
Why do you divide by the average?
Because neither number is the starting point. If you divided by the first number you would get a different answer from dividing by the second. The average sits between them, so both numbers are treated fairly and the order stops mattering.
Does the order of the numbers matter?
No. The gap is the same size either way, and the average is the same either way, so 80 and 100 give the same 22.22 percent as 100 and 80. This is the main way percentage difference differs from percent change, where the order changes the answer.
Can percentage difference be negative?
No. The formula uses the size of the gap, so the answer is zero or positive. If you want to know whether a value is above or below another one, use the compare to a target mode or the percent change, which show a direction.
Can percentage difference be more than 100 percent?
Yes. Two positive numbers can be up to 200 percent apart. For example, 10 and 90 have a gap of 80 and an average of 50, so the difference is 160 percent. The largest possible answer for positive numbers is 200 percent, which happens when one number is 0.
How do I find the percentage difference in Excel or Google Sheets?
With the numbers in A1 and B1, type =ABS(A1-B1)/AVERAGE(A1,B1) in another cell and format that cell as a percentage. Excel and Sheets multiply by 100 for you when the cell is formatted as a percent.
What is the percentage difference between 0 and a number?
It is always 200 percent, as long as the other number is not 0. For 0 and 50 the gap is 50 and the average is 25, and 50 divided by 25 is 2, which is 200 percent. Because of this, percentage difference is not a good choice when one value is 0.
When should I use percentage difference instead of percent change?
Use percentage difference when two values are equal in importance, such as two prices in different shops, two groups in a survey or two measurements of the same thing. Use percent change when one value came first and the other came later, such as a price before and after a sale.
How do I find the percentage difference between three or more numbers?
The formula is made for two numbers. For a group, you can compare each number with the average of the whole group, or compare the highest and the lowest. Say clearly which method you used, because different methods give different answers.
Is percentage difference the same as percentage points?
No. Percentage points are used when you subtract one percentage from another. If a rate moves from 10 percent to 12 percent, that is 2 percentage points. The percentage difference between 10 and 12 is 18.18 percent. These are two different questions.
About the author
Umar Khan is a PhD student in engineering at NTNU. He writes and checks the maths on UtilMora.
For information only, not professional advice.
Written by Umar Khan. Last updated: November 2, 2026.