Percentage Difference Calculator
Compares two positive numbers. The order does not matter.
This is a worked example. Clear the fields and enter your own values, then press Calculate.
PERCENTAGE DIFFERENCE
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Percentage Difference Calculator
Percentage Calculators
Percentage difference answers a specific question: how far apart are two values, expressed as a percentage, when neither one is treated as the “original” or “correct” figure? This percentage difference calculator compares Value A and Value B using their average as the shared base, which is what makes it different from percentage change or percentage error, and why the order you enter the two numbers doesn’t affect the result.
How to use this percentage difference calculator
- Enter Value A in the first field.
- Enter Value B in the second field.
- Click Calculate to see the Percentage Difference and the full Solution steps.
- Click Clear to reset both fields and start over.
What this percentage difference calculator does
The calculator takes two positive numbers and expresses the gap between them as a percentage of their average, rather than as a percentage of either one individually. Because the average of A and B is the same regardless of which one you call “A” and which you call “B,” swapping the two values you enter produces exactly the same result, unlike percentage change or percentage error, where order matters because one value is treated as the starting or reference point.
The percentage difference formula
Percentage Difference = |A − B| ÷ ((A + B) ÷ 2) × 100
The numerator takes the absolute difference between the two values, so the result is always positive regardless of which number is larger. The denominator uses the average of A and B as the base for comparison, which is the key distinction from percentage change: there is no “before” and “after” here, just two values being compared on equal footing.
Why order doesn’t matter here
Because the formula uses |A − B| (an absolute value) in the numerator and the average of both numbers in the denominator, entering 70 and 85 gives exactly the same percentage difference as entering 85 and 70. This is intentional and is what separates this calculator from a percentage change or percentage increase/decrease calculation, where swapping the start and end values would produce a different (and differently signed) result.
When to use percentage difference instead of percentage change
| Situation | Use this calculator (percentage difference) | Use a percentage change calculator instead |
|---|---|---|
| Comparing two measurements from different sources with no clear “original” | Yes | No |
| Comparing a before and after value over time | No | Yes |
| Comparing two prices, scores, or quantities where neither is the baseline | Yes | No |
| Tracking growth or decline from a known starting point | No | Yes |
Percentage difference is the right tool when you’re comparing two independent values side by side, for example two competitors’ prices, two lab measurements of the same quantity, or two survey results, where it doesn’t make sense to call one of them the “starting point.”
Frequently asked questions
Does it matter which value I enter as Value A and which as Value B?
No. Because the formula uses the absolute difference between the two values and their average as the base, entering the numbers in either order produces the same percentage difference.
What’s the difference between percentage difference and percentage change?
Percentage difference compares two values with neither treated as the original, using their average as the base, and is always positive. Percentage change compares a starting value to a final value, treating the starting value as the base, and can be positive (increase) or negative (decrease) depending on the direction of change.
Can I use this calculator with negative numbers?
This calculator is built for comparing two positive numbers. If you need to compare a value that changed from one point in time to another, including cases involving negative numbers, a percentage change or percentage increase/decrease calculator is the more appropriate tool.