Coefficient of Variation Calculator
Paste a data set to get its coefficient of variation (relative standard deviation) as a percentage, with the mean and standard deviation.
The coefficient of variation (CV), also called the relative standard deviation, expresses the spread of a data set as a percentage of its mean. Because it has no units, it lets you compare variability between data sets on different scales: the consistency of two machines, the volatility of two prices or the precision of a lab assay. Paste your numbers to get the CV, mean and standard deviation.
How to use this tool
- Paste or type your values, separated by commas, spaces or new lines.
- Choose sample (most data) or whole population (you measured every member).
- Read the CV as a percentage, together with the mean and standard deviation it was built from.
Formula
CV = (s / |x̄|) × 100%
s is the standard deviation and x̄ the mean. The sample standard deviation divides the sum of squared deviations by n − 1; the population version divides by n. A lower CV means the values sit more tightly around their mean.
Example
For the values 2, 4, 4, 4, 5, 5, 7, 9 the mean is 5. Treated as a whole population the standard deviation is 2, so CV = 2 / 5 = 40%. Treated as a sample, s = √(32 / 7) ≈ 2.1381 and the CV is about 42.76%.
Frequently asked questions
What is a good coefficient of variation?
It depends on the field. The acceptable CV depends on the measurement method, concentration range and intended use; a single numerical threshold is not universal. Compare against what is typical for your kind of measurement rather than one universal cut-off.
Can I use the CV with negative numbers?
Only with care. The CV is meant for ratio-scale data with a true zero, such as weights, times or prices. With temperatures in °C or data that cross zero, the mean can sit near zero and the CV becomes huge or meaningless.
Is the coefficient of variation the same as relative standard deviation?
Yes. RSD is the name used in chemistry and quality control; it is the same s / x̄ × 100%.
Should I choose sample or population?
Use sample when your numbers are a subset of a larger group you want to describe, which is the usual case. Use population only when you have every value.
Last updated: 2026-10-30