Percentage difference calculator
Calculator
The calculator needs JavaScript. The tables below give the same numbers for common cases.
How it is worked out
- Difference: |80 − 100| = 20.
- Average: (80 + 100) ÷ 2 = 90.
- Divide and multiply by 100: 20 ÷ 90 × 100 = 22.2222%.
| Inputs | Answer |
|---|---|
| 80, 100 | The percentage difference between 80 and 100 is 22.2222%. |
| 12, 15 | The percentage difference between 12 and 15 is 22.2222%. |
| 500, 450 | The percentage difference between 500 and 450 is 10.5263%. |
How to use it
Percentage difference = |a − b| ÷ ((a + b) ÷ 2) × 100. It uses the average of the two values as the base, so swapping them gives the same answer.
Use it when neither value is the "old" one, such as comparing two prices or two measurements. If one is clearly the starting value, percent change is the better choice.
Frequently asked questions
How is percentage difference different from percent change?
Percent change uses the old value as the base; percentage difference uses the average of both, so the order does not matter.
What is the difference between 80 and 100?
20 ÷ 90 × 100 = 22.22%.
Can it be over 100%?
Yes, when the two values are far apart.
Method: standard arithmetic shown step by step; no outside data is used. Checked 2026-11-12.
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General information only. Results are plain arithmetic on the numbers you enter; check anything important (money, health, school work) against your own records or the official source.