Percentage Difference Calculator
Percentage difference compares two numbers when neither one is the “starting point” — two shops’ prices, two students’ results, two measurements of the same thing. It uses the average of the two as the reference, so swapping A and B gives the same answer.
Answer
The difference between 45 and 55 is 20% of their average.
Step by step
- Absolute difference: |45 − 55| = 10.
- Average of the two: (45 + 55) ÷ 2 = 50.
- Divide: 10 ÷ 50 = 0.2.
- Multiply by 100: 20%.
Answer: 20%
Still stuck? Ask the tutor about these steps
How it works
|A − B| ÷ ((A + B) ÷ 2) × 100Find the gap between the values and ignore the sign.
Find the average of the two values; this is the fair middle reference point.
Divide the gap by the average and multiply by 100.
If one value clearly came first (an old and a new price), use percent change instead — it divides by the original value, not the average.
Worked example
One shop sells a book for $45 and another for $55. What is the percentage difference?
- |45 − 55| = 10
- (45 + 55) ÷ 2 = 50
- 10 ÷ 50 × 100 = 20%
Frequently asked questions
What is the difference between percent change and percentage difference?
Percent change divides by the original value and has a direction (increase or decrease). Percentage difference divides by the average and has no direction.
Does the order of the numbers matter?
No. Because it uses the absolute difference and the average, A vs B and B vs A give the same result.