This calculator works out the coefficient of variation (CV) of a set of numbers. Type or paste the values separated by commas; you get the CV in percent, the mean and the sample standard deviation.
Formula
CV = s ÷ x̄ × 100%, where x̄ is the mean and s the sample standard deviation, s = √(Σ(x − x̄)² ÷ (n − 1)).
Worked Example
Values 12, 15, 11, 18 and 14.
- Mean = 70 ÷ 5 = 14.00
- Squared deviations: 4, 1, 9, 16, 0; sum 30
- s = √(30 ÷ 4) = √7.5 = 2.7386
- CV = 2.7386 ÷ 14 × 100 = 19.56%
How to read the result
CV compares spread across data with different scales or units: a CV of 5% is tight, 50% is very variable. Lab methods often report CV for repeat measurements.
Limits and common mistakes
- CV is not meaningful when the mean is near zero or the data can be negative (such as temperatures in °C).
- Some sources use the population standard deviation; this page uses the sample one.
Frequently Asked Questions
What is a good CV?
It depends on the field; repeat lab measurements often aim for under 10%.
Sample or population SD?
This page uses the sample SD (n − 1).
Can CV be over 100%?
Yes, when the standard deviation is bigger than the mean.
Does CV have units?
No; it is a ratio, shown in percent.
Formula used
list x | Values | 12, 15, 11, 18, 14 out cv | Coefficient of variation | % | sd(x) / mean(x) * 100 | 2 out mn | Mean | - | mean(x) | 2 out sdv | Sample standard deviation | - | sd(x) | 4
Each line is one input (in, sel, list) or one result (out: label, unit, formula, decimals). How the calculators work
Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.