Coefficient of Variation Calculator
Find the coefficient of variation (CV) — the standard deviation as a percentage of the mean — to compare the relative spread of different data sets.
Quick answer: CV = (standard deviation ÷ mean) × 100%. For a standard deviation of 15 and a mean of 100, CV = (15 ÷ 100) × 100 = 15%. A lower CV means less relative variability.
The coefficient of variation expresses variability relative to the mean, so it lets you compare the spread of data sets that are measured on different scales — say, incomes versus test scores. Because it's a ratio, it drops the units and is often reported as a percentage.
The formula
CV = (standard deviation ÷ mean) × 100%
Worked example
A process has a mean of 50 and a standard deviation of 5. CV = (5 ÷ 50) × 100 = 10%. A second process with mean 200 and SD 5 has CV = 2.5% — less relative variability even though the SD is the same.
Frequently asked questions
How do I calculate the coefficient of variation?
Divide the standard deviation by the mean and multiply by 100 to get a percentage.
Why use CV instead of standard deviation?
CV is relative and unitless, so it compares spread fairly across data sets with different means or units.
What is a good coefficient of variation?
It depends on the field, but a lower CV means more consistency. Interpretation is always context-specific.
Can CV be used with negative data or a zero mean?
It's meaningful only for ratio data with a positive mean; it breaks down when the mean is zero or the data include negatives.
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