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Coefficient of Variation Calculator
The coefficient of variation (CV) is the standard deviation divided by the mean, usually expressed as a percentage. Because it has no units, it lets you compare the spread of data sets measured on different scales, for example the variability of exam scores out of 50 against scores out of 100, or of prices in different currencies.
Enter your data and choose the sample or population standard deviation. The calculator finds the mean, the standard deviation and the ratio, and shows each step. A CV of 10% means the typical deviation from the mean is a tenth of the mean; in laboratory work a CV under 5% is often the target for a repeatable assay, while in finance the CV of returns is a simple risk-per-unit-of-return measure.
The CV is only meaningful for data measured on a ratio scale with a positive mean. It is not appropriate for temperatures in °C or for data whose mean is close to zero, where the ratio becomes unstable.
Separate values with commas, spaces or new lines.
Result and step-by-step solution
The standard deviation is 11.3% of the mean.
- Meanx̄ = Σx ÷ n = 25.5 (n = 8)
- Sample standard deviations = √[Σ(x − x̄)² ÷ (n − 1)] = √(58 ÷ 7) = 2.8785
- CV = s ÷ |x̄| × 100%2.8785 ÷ 25.5 × 100% = 11.29% (as a ratio: 0.1129)
Frequently asked questions
- What is a good coefficient of variation?
- It depends on the field. Analytical chemistry often aims for under 5%, manufacturing tolerances vary, and survey or biological data commonly show CVs of 20–30% or more. Compare against benchmarks from your own discipline.
- Can the coefficient of variation be negative?
- Only if the mean is negative. The calculator uses the absolute value of the mean so the CV reflects spread alone; if your mean is negative the CV is usually not a useful measure.
- Sample or population SD for the CV?
- Use the sample SD (n − 1) when the data is a sample. Use the population SD when you have every value of interest. The two differ little for large n.
- How is the CV different from the standard deviation?
- The SD is in the units of the data; the CV is the SD relative to the mean, so it is unit-free and comparable across different scales.
Last reviewed: September 25, 2026. Calculations run in your browser and were validated against SciPy.