Coefficient of Variation Calculator
Compare relative variability between data sets with different units or scales.
What the Coefficient of Variation Calculator does
The coefficient of variation expresses standard deviation as a percentage of the mean. Because it is unitless, it lets you compare the consistency of measurements taken in completely different units — say rainfall in millimetres against temperature in degrees.
Formula
CV = (Standard deviation ÷ |Mean|) × 100
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Input method | one of 2 options | Yes | — |
| Data set | text | In some modes | Separate values with commas, spaces or new lines. Shown Input method is Raw data. |
| Mean | number | In some modes | Shown Input method is Mean and standard deviation. |
| Standard deviation | number | In some modes | Accepts 0 or more. Shown Input method is Mean and standard deviation. |
| Data set type | one of 2 options | Yes | — |
How to use it
- Choose Input method and Data set type.
- Fill in the remaining inputs the form shows for your choice.
- Select Calculate.
Worked example
A process with a mean of 250 and a standard deviation of 18.
- Mean
- 250
- SD
- 18
18 ÷ 250 × 100 = 7.2% — low variability, a consistent process.
Frequently asked questions
When is CV not appropriate?
When the data can take negative values or the mean sits near zero. Temperature in Celsius is the classic failure case — the ratio becomes meaningless around freezing.
What counts as a good CV?
It is context-dependent. Laboratory assays often require under 15%; financial returns routinely exceed 100%.