Coefficient of Variation Calculator
The relative variability of data: standard deviation ÷ mean × 100.
Result
Coefficient of variation (%)
15.00
How it works
The coefficient of variation expresses dispersion relative to size: CV = standard deviation ÷ mean × 100. A standard deviation of 5 around a mean of 100 is a CV of 5%; the same 5 around a mean of 10 is 50% — the second dataset is far more variable in any meaningful sense. That relativity is the whole point. A standard deviation is expressed in the units of the data, so it cannot compare a set of salaries with a set of heights, or a machine measuring millimetres with one measuring metres. Dividing by the mean strips out both the unit and the scale, leaving a pure percentage. As loose landmarks, a CV under 10% usually indicates tight consistency and above 30% substantial variability — but the thresholds are field-dependent. Laboratory assays demand single digits, while biological and economic data routinely and legitimately run far higher.
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Frequently asked questions
Why use CV instead of SD?
CV is unitless, so it compares variability across datasets with different means or units.
What is a high CV?
It depends on the field, but a higher CV means more relative spread around the mean.
Does the CV work with negative values?
No. A mean near zero makes the ratio explode, and a negative mean makes the sign meaningless. Use the CV only on ratio-scale data that stays positive — never on temperatures in Celsius or on profit-and-loss figures.
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