The coefficient of variation (CV) is the standard deviation divided by the mean, usually shown as a percentage. It measures spread relative to the size of the values.
Coefficient of variation = Standard deviation ÷ Mean × 100
On the 30-day sample below: 21.39%.
When to use it
It lets you compare how volatile things of different sizes are: a store doing 30 orders a day and one doing 3,000 can be compared on CV but not on standard deviation.
Worked example
Format the Excel result as a percentage. A CV of around 20% means a typical day is about a fifth away from the average day.
=STDEV.S(C2:C31)/AVERAGE(C2:C31)| Day | Website orders |
|---|---|
| 1 | 24 |
| 2 | 27 |
| 3 | 22 |
| 4 | 30 |
| 5 | 28 |
| 6 | 25 |
| 7 | 31 |
| 8 | 29 |
| 9 | 26 |
| 10 | 33 |
| 11 | 30 |
| 12 | 28 |
| 13 | 35 |
| 14 | 32 |
| 15 | 29 |
| 16 | 34 |
| 17 | 61 |
| 18 | 31 |
| 19 | 36 |
| 20 | 33 |
| 21 | 30 |
| 22 | 37 |
| 23 | 35 |
| 24 | 32 |
| 25 | 38 |
| 26 | 36 |
| 27 | 34 |
| 28 | 40 |
| 29 | 37 |
| 30 | 39 |
Common mistakes
- Only meaningful for values on a ratio scale with a true zero (counts, money). Not for temperatures or scores that can be negative.
- When the mean is close to zero the CV explodes and means nothing.
- It inherits the standard deviation's sensitivity to outliers.
Calculate it yourself
Related methods
See all statistics methods or the business metrics they are used on.
Further reading
Questions people ask
- What is coefficient of variation?
- The coefficient of variation (CV) is the standard deviation divided by the mean, usually shown as a percentage. It measures spread relative to the size of the values.
- What is the formula for coefficient of variation?
- Coefficient of variation = Standard deviation ÷ Mean × 100. On the 30-day sample data the result is 21.39%.
- How do you calculate coefficient of variation in Excel?
- Use =STDEV.S(C2:C31)/AVERAGE(C2:C31) with the data in rows 2 to 31. The same formula works in Google Sheets.
About the data on this page
The figures come from a small made-up dataset, printed above in full so you can check every number by hand. Download it as daily.csv. The results are computed from those rows when the page is built, and the Excel formulas, SQL and Python on these pages are run against the same rows before publishing, so the code and the answers agree.
To get these numbers from your own data without writing formulas, try AnalyzeIt: ask in plain words and it shows the working behind every figure.
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