Coefficient of Variation Calculator

The coefficient of variation (CV) is the ratio of the standard deviation to the mean, expressed as a percentage. It measures relative variability, making it useful for comparing the spread of datasets with different units or scales. A lower CV indicates less variability relative to the mean, while a higher CV indicates greater variability.

The CV formula is: CV = (σ / μ) × 100%, where σ is the standard deviation and μ is the mean. For a sample, you use the sample standard deviation (dividing by n−1); for a population, you use the population standard deviation (dividing by n). This calculator handles both modes automatically.

When your data represents a subset (sample) of a larger group, you use the sample standard deviation, which divides by n−1 to correct for bias. When your data represents the entire group (population), you use the population standard deviation, dividing by n. The choice affects the standard deviation and therefore the CV result.

CV is particularly useful when comparing variability between datasets with different units or very different means — for example, comparing the variability of heights in centimeters vs. weights in kilograms. It's widely used in finance, biology, engineering, and quality control to assess relative risk or consistency.

Avoid using CV when the mean is zero or close to zero, as this makes the ratio undefined or extremely large and misleading. It is also not appropriate for data measured on interval scales (like temperature in Celsius) where zero does not represent an absence of the measured quantity.

The coefficient of variation and relative standard deviation (RSD) are essentially the same measure. Both express the standard deviation as a percentage of the mean. The term 'RSD' is more commonly used in analytical chemistry and laboratory sciences, while 'CV' is used more broadly across statistics and research.

There is no universal threshold for a 'good' CV — it depends entirely on the field and context. In biology or clinical labs, a CV below 10–15% is often considered acceptable. In finance, CV helps compare investment risk. Generally, a lower CV means more consistency, but what counts as 'low' varies by discipline.

Simply type or paste your numbers into the data input field, separated by commas, spaces, or line breaks. For example: 10, 34, 23, 54, 9. Then select whether your data is a sample or a full population and click Calculate to see your results.