Free Percentage Difference Calculator

Two numbers, no clear "before" or "after" just two values you want to compare. That's exactly what this percentage difference calculator is built for.

Unlike increase or decrease, order doesn't matter here. Enter the two numbers either way round and you get the same answer.

Need direction to matter instead? Try the Percentage Increase or Percentage Decrease Calculator. Or check out the Logarithm Equation Calculator or the full calculator list.

Percentage Difference Calculator

Both numbers need to be positive and greater than 0. Whole numbers or decimals both work.

Not the Same as Percentage Change
  • Percentage difference treats both numbers equally there's no "starting" number, so the order you enter them in doesn't change the answer.
  • Percentage change (increase/decrease) assumes one number came before the other, so swapping the order flips the sign of the result.

Answer

Solution:

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Opens with both numbers already filled in and the answer showing.

Enter two positive numbers and the percentage difference, worked out step by step, will appear here.

How to Use This Calculator

You just need two numbers. That's it.

  1. Drop your first number into V1.
  2. Drop the second one into V2. It genuinely doesn't matter which number goes where you'll get the same result either way.
  3. Hit Calculate and you'll see the percentage difference right away, with each step of the math shown below it so you're not just staring at a number wondering how it got there.
  4. Copy the answer, print a clean version of just your numbers and the working, or grab a share link if you want to send the exact calculation to someone else without them having to type anything in themselves.
  5. Clear wipes both fields if you want to try new numbers.

The Formula, With a Real Example

% difference = [ |V1 − V2| ÷ ((V1 + V2) ÷ 2) ] × 100

In plain words: take the gap between the two numbers, divide it by their average, then turn that into a percent. The absolute value bars just mean you ignore whether the gap is positive or negative a difference is a difference, either direction.

Quick example. What's the percentage difference between 5 and 7?

|5 − 7| = 2
(5 + 7) ÷ 2 = 6
2 ÷ 6 = 0.333
0.333 × 100 = 33.33%

Flip it, use 7 and 5 instead, and you'd still land on 33.33%. That's the whole point of this being a "difference" rather than a "change."

Why Use This Instead of Just Subtracting?

  • Raw subtraction only tells you the gap in absolute terms. A gap of 50 means something completely different if the numbers are around 100 versus around 100,000, and percentage difference accounts for that scale.
  • It saves you from mixing this up with percentage change, which is a common mistake. If there's no "before" number in your comparison, this is the right tool, not that one.
  • You get the full working, not just a final figure, which is handy if you need to show your math or just want to double check it.
  • Averaging the two numbers in the denominator (rather than picking one as the "base") keeps the comparison fair when neither number is obviously the reference point.

What Each Part of the Formula Means

  • V1 and V2 - your two numbers, in whichever order you want to type them.
  • |V1 − V2| - the gap between them, always taken as a positive number.
  • (V1 + V2) ÷ 2 - the average of the two numbers, used as the baseline the difference is measured against.
  • The result - how big that gap is, expressed as a percentage of the average. There's no increase or decrease label here, because neither number is treated as "first."

Frequently Asked Questions

No, not at all. That's really the whole point of percentage difference over percentage change swap the two numbers around and you'll get the exact same result, since the formula treats them equally.

They sound alike but they answer different questions. Percentage change assumes one number came before the other and tells you how much it moved. Percentage difference just compares two numbers side by side with no timeline involved, using their average as the baseline instead of picking one as the "start."

No, this only works with positive numbers above zero. If one of your values is negative, the averaging in the denominator can produce misleading or undefined results, so percentage difference isn't the right tool in that case.

Picking one number as the base would make the order matter again, which defeats the point. Averaging both numbers keeps things fair since neither value is being treated as more important than the other.

No, It only carries the exact V1 and V2 values you typed in, nothing more.

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