MyToolsLab Runs in your browser

Business & Calculators

Percentage Difference Calculator

Enter two values to see how far apart they are as a percentage of their average, step by step.

Private by design — your data stays on your device.

and

Percentage difference

22.2222%

|80 − 100| = 20
(80 + 100) ÷ 2 = 90
20 ÷ |90| × 100 = 22.2222%

Percentage change from A to B

+25%

(100 − 80) ÷ |80| × 100 = +25%
increase

The percentage difference is the same whichever value you enter first. The percentage change depends on the order.

What does the percentage difference calculator do?

Percentage difference compares two values on equal terms: it divides the gap between them by their average, so swapping the values gives the same answer. Percentage change is different, because it measures a move from a starting value to a new one and divides by the starting value. This calculator shows both, with the working for each.

How to use the percentage difference calculator

  1. Enter one value in A and the other in B. You can use a decimal point or a decimal comma.
  2. Read the percentage difference and the working under it: the gap, the average and the division.
  3. If one value came first, read the percentage change from A to B as well.
  4. Copy either result with one click.

Your privacy

All calculations run in your browser. The numbers you enter are not sent or stored anywhere.

Read how MyToolsLab handles privacy

Frequently asked questions

What is the percentage difference formula?

Percentage difference = |A − B| ÷ ((A + B) ÷ 2) × 100. For 80 and 100, the gap is 20 and the average is 90, so the difference is 20 ÷ 90 × 100 = 22.22%.

When should I use percentage difference instead of percentage change?

Use percentage difference when neither value is the starting point, such as two prices from different shops or two measurements of the same thing. Use percentage change when one value came first: 80 to 100 is a 25% increase, but 100 to 80 is a 20% decrease.

What happens if a value is zero?

If both values are the same, including both zero, the difference is 0%. If the values differ but average to zero, such as −5 and 5, the percentage difference is undefined and the calculator says so. Percentage change from a starting value of zero is also undefined.

Can I use negative numbers?

Yes, but the result is easiest to interpret for positive values. With negative numbers the calculator divides by the size of the average (its absolute value), so the percentage difference is never negative.