Percentage Difference Calculator

Percentage difference formula

percentage difference = |A − B| ÷ ((A + B) ÷ 2) × 100

You divide the gap between the two numbers by their average, then multiply by 100. Because the average sits in the middle, neither number is treated as the starting point: swap A and B and the result stays the same.

How to calculate percentage difference, step by step

Say one store sells a pair of headphones for $42 and another sells the same pair for $54.

1. Find the gap. |42 − 54| = 12. The bars mean you drop the minus sign.
2. Find the average. (42 + 54) ÷ 2 = 48.
3. Divide the gap by the average. 12 ÷ 48 = 0.25.
4. Multiply by 100. 0.25 × 100 = 25%.

The two prices differ by 25%. The calculator shows these steps under the result, filled in with your own numbers.

Percentage difference or percentage change?

Both compare two numbers, but they answer different questions.

• Use percentage difference when neither value comes first: two stores, two lab measurements, two candidates, two suppliers. The answer has no direction.
• Use percentage change when one value is the before and the other is the after: last month's sales and this month's, an old price and a new one. The answer has a direction and depends on the starting point.

With the same two prices you get three different figures:

The calculator above shows all three at once, so you can pick the one that fits your question. For other percentage questions, such as finding 15% of a number or adding 20% to a price, use the Percentage Calculator.

Comparing two percentages: points or percent?

When the two values are already percentages, there are two honest ways to describe the gap, and they give very different numbers.

Take two landing pages with conversion rates of 2.5% and 3.5%:

• The gap is 1 percentage point (3.5 − 2.5).
• The percentage difference is 33.33% (1 ÷ 3 × 100).
• Going from the first page to the second is a 40% increase (1 ÷ 2.5 × 100).

All three are correct. Saying "1 point" is the clearest way to report a gap between rates. If you write "a 33% difference" or "40% better", say which of the two calculations you used, or readers may assume the rate itself rose by 33 or 40 points.

Percentage difference in Excel and Google Sheets

With the two values in A2 and B2, the formula is the same in Excel and Google Sheets:

=ABS(A2-B2)/AVERAGE(A2,B2)

Format the cell as a percentage (the % button in the toolbar) and the result shows as 25% for the prices above. Without that format you will see 0.25.

If your data can contain negative numbers, wrap the average in ABS too, which matches what this calculator does:

=ABS(A2-B2)/ABS(AVERAGE(A2,B2))

For a percentage change from A2 to B2, use =(B2-A2)/ABS(A2) instead. Both formulas return #DIV/0! when the number they divide by is zero, for the reasons in the next section.

When the formula breaks: zero and negative numbers

Zero and a positive number. The percentage difference between 0 and any positive number is always 200%: between 0 and 10, the gap is 10 and the average is 5. For two numbers that are zero or positive, 200% is also the largest possible result, so a percentage difference above 100% is normal and only means the values are far apart.

Opposite values. For −5 and 5 the average is 0, and the formula would divide by zero. There is no meaningful percentage difference, and the calculator says so instead of showing a number.

Negative numbers. With values below zero, such as temperatures or account balances, the result depends on how the average is handled, and different tools disagree. This calculator uses the size of the average, so −4 and −6 give 40%. For data that crosses zero or sits close to it, the plain gap (here 2) is usually the more useful thing to report.

Your numbers stay on this device

The calculation runs in your browser. Nothing you type is sent to a server or stored.