# How to calculate the percentage difference between two numbers in Excel

Divide the absolute difference by the average of the two: `=ABS(B2-C2)/AVERAGE(B2,C2)`.

**Excel:** `=ABS(B2-C2)/AVERAGE(B2,C2)` (Every current version)

**Google Sheets:** the same formula works.

## Example

Sample data (row 1 is the header):

| A | B | C | D |
| --- | --- | --- | --- |
| Item | Quote A | Quote B | Difference |
| Laptop repair | 120 | 100 |  |
| Cleaning | 45 | 50 |  |
| Delivery | 80 | 80 |  |
| Installation | 200 | 150 |  |
| Cables | 12 | 15 |  |

Formula in D2, filled to D6: `=ABS(B2-C2)/AVERAGE(B2,C2)`

Result: 18.2%; 10.5%; 0.0%; 28.6%; 22.2%

## How it works

Percentage difference compares two values when neither is the "before": it divides the gap by their average, so swapping A and B gives the same answer. 120 and 100 differ by 20, and their average is 110, so they are 18.2% apart.

Use percentage change instead when one value is the starting point.

## Other ways

- `=(C2-B2)/B2`: Percentage change from A to B. Use it when A is the baseline. (Not symmetric: 120 to 100 is a 16.7% decrease, but 100 to 120 is a 20% increase.)

## Common mistakes

- Percentage difference and percentage change are different measures. Pick the one that matches the question, and name it in the report.
- If both values are 0, the formula divides by zero. Guard it with `=IF(AVERAGE(B2,C2)=0,0,ABS(B2-C2)/AVERAGE(B2,C2))`.

## Questions

**Which one do I divide by, the bigger or the smaller number?**

Neither: percentage difference uses the average of the two. Dividing by one of them is percentage change.

**How do I flag quotes that differ by more than 10%?**

Compare the result: `=ABS(B2-C2)/AVERAGE(B2,C2)>10%`.

Every formula and result on this page was checked by running it in the Spreadsheet Practice formula engine on 2026-10-30.

Source: https://spreadsheetpractice.com/formulas/percentage-difference-between-two-numbers