Percentage Difference Calculator
This percentage difference calculator compares two numbers and tells you how far apart they are as a percent. Enter the two values in any order, and it works out the gap against their average, which is the proper way to measure difference when neither number is the starting point. You'll get the answer with the steps, plus the change from one to the other, so you can pick the figure you actually need.
- Order does not matter
- Shows the steps
- Live bar
- Average and gap
- Change shown too
Last updated June 16, 2026 Formula: |a − b| ÷ average × 100 Reviewed by the Calcowa math team
Compare two numbers
Enter two numbers to see the answer.
|40 − 60| ÷ ((40 + 60) ÷ 2) × 100 = 40%
What is percentage difference?
Percentage difference measures how far apart two numbers are, as a percent of their average. It's the fair way to compare two values when neither one is a starting point, like two lab readings or two prices from different shops. You take the gap between them, divide by their average, and multiply by 100. Because it uses the average, the order of the two numbers doesn't change the answer.
How do you calculate percentage difference?
Here's how to find the percentage difference between 40 and 60:
- 1
Find the gapSubtract and drop the sign: |40 − 60| = 20.
- 2
Find the averageAdd and halve: (40 + 60) ÷ 2 = 50.
- 3
Divide and multiply20 ÷ 50 × 100 = 40%, so the percentage difference is 40%.
Percentage difference vs percentage change
This trips up a lot of people, so here's the clear version. Percentage difference compares two values with no "before" or "after", so it divides by their average and is always positive. Percentage change has a clear original value and divides by that, so the order matters and it turns negative for a drop. If you're tracking something over time, like a price last month and this month, you want change, and the percentage increase calculator handles that. The result above shows the change too, so you've got both.
Percentage difference between two numbers
To get the percentage difference between two numbers, you only need the two values, since the calculator figures out the gap and the average for you. For 10 and 12, the gap is 2 and the average is 11, so the difference is 2 ÷ 11 × 100 = 18.18%. It works the same whether the numbers are tiny or huge, because everything is measured against their own average.
Difference between two percentages
When you compare two percents, like 20% and 35%, the plain gap of 15 is called 15 percentage points, not a 15% difference. Percentage points are just the subtraction of the two percents, while a true percentage difference would divide by their average. News reports often blur this line, so it's worth keeping the two ideas apart when the numbers are themselves percentages.
Percentage difference examples
| Two numbers | Difference |
|---|---|
| 40 and 60 | 40% |
| 10 and 12 | 18.18% |
| 100 and 150 | 40% |
| 8 and 8 | 0% |
| 25 and 75 | 100% |
Frequently asked questions
Does the order of the two numbers matter?
No. Percentage difference divides by the average of the two numbers, so you'll get the same answer whichever value you type first. That's what makes it a fair comparison rather than a before-and-after measure.
Take the absolute difference between the two numbers, divide by their average, then multiply by 100. For 40 and 60, that's |40 − 60| ÷ ((40 + 60) ÷ 2) × 100 = 20 ÷ 50 × 100 = 40%. The order of the two numbers doesn't matter, because you use the gap and the average.
It's |a − b| ÷ ((a + b) ÷ 2) × 100. The top is the size of the gap, and the bottom is the average of the two values. Since neither number is treated as the starting point, swapping them gives the same answer.
Percentage difference compares two values fairly, with no "before" or "after", so it divides by their average. Percentage change has a clear starting value and divides by that old value instead. If you're tracking growth over time, you want change; if you're comparing two readings, you want difference.
Subtract to get the gap, ignore the minus sign, divide by the average of the two numbers, and multiply by 100. For 10 and 12, the gap is 2, the average is 11, so it's 2 ÷ 11 × 100 = 18.18%. Type both numbers above and it's done for you.
Yes. Percentage difference uses the absolute gap, so it can't be negative. That's another way it differs from percentage change, which goes negative when a value drops.
That gap is 15 percentage points, not a 15% difference. "Percentage points" is the plain subtraction of two percents, while a percentage difference would divide by their average. Mixing the two up is a common mistake in reports and news.
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Comparing or tracking?
Use difference to compare, or the percentage calculator for everything else.