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Coefficient of Variation Calculator

Calculate the coefficient of variation - a standardized measure of data spread relative to the mean.

Result

Coefficient of Variation
12.22%
Mean
25
Standard Deviation
3.055

About the Coefficient of Variation

The Coefficient of Variation Calculator expresses the spread of a dataset as a percentage of its mean, rather than in the dataset's original units. That makes it possible to compare how variable two datasets are relative to their own scale, even when one is measured in dollars and the other in kilograms, or when their averages are very different in size.

How It Works

Enter a list of numbers separated by commas or spaces. The calculator finds the mean of the list, then computes the sample standard deviation (using an n-1 denominator), and finally divides the standard deviation by the mean and multiplies by 100 to express the result as a percentage.

CV = (Sample Standard Deviation / Mean) x 100%, where sample standard deviation uses an n - 1 denominator.

Formula & Methodology

By hand, add up all values and divide by the count to get the mean. Subtract the mean from each value, square each difference, add those squares together, and divide by one less than the number of values to get the sample variance; take its square root for the sample standard deviation. Divide that standard deviation by the mean and multiply by 100 for the percentage.

Examples

Seven measurements averaging 25

For the values 22, 24, 25, 27, 30, 21, and 26, the mean is 25 and the sample standard deviation is about 3.06, giving a coefficient of variation of roughly 12.2%.

Five tightly clustered product weights

For product weights of 100, 102, 98, 101, and 99 grams, the mean is 100 and the sample standard deviation is about 1.58, giving a much lower coefficient of variation of roughly 1.6%, reflecting a far more consistent batch than the first example.

Advantages

  • Puts variability on a percentage scale, making it possible to compare spread across datasets with different units or magnitudes.
  • Calculates the mean and sample standard deviation for you as intermediate results, so you can double-check the underlying numbers.
  • Works with any list of numeric data pasted in as comma or space separated values, without needing a formatted spreadsheet.

Common Mistakes

  • Comparing coefficient of variation values across datasets with means close to zero, where the metric becomes unstable or misleading even when technically defined.
  • Mixing up population and sample standard deviation conventions when comparing this calculator's output to a value computed elsewhere with a different denominator.
  • Applying CV to data that isn't measured on a ratio scale with a true, meaningful zero, where dividing by the mean doesn't produce a meaningful percentage.

Edge Cases to Watch For

  • At least 2 numbers are required, since the sample standard deviation formula divides by n - 1 and is undefined for a single value.
  • If the mean of the dataset is exactly zero, the coefficient of variation is mathematically undefined and the calculator returns an error rather than a divide-by-zero result.
  • The calculator always uses the sample standard deviation (n - 1), not the population standard deviation (n); for very small samples this makes the reported CV slightly larger than a population-based calculation would.

Common Use Cases

  • Quality control analysts comparing consistency of a manufacturing process across product lines with different target measurements.
  • Finance professionals comparing the relative volatility of investments with very different average returns or price levels.
  • Lab scientists comparing measurement precision between instruments or methods that report in different units or ranges.
Written & fact-checked by the Calculateus TeamLast updated August 5, 2026How we verify our formulas

Frequently asked questions

Why use coefficient of variation instead of standard deviation alone?

Standard deviation is in the same units as the data, which makes it hard to compare spread across datasets with very different scales or units - CV expresses spread as a percentage of the mean, letting you compare relative variability between, say, a dataset in dollars and one in kilograms.

Related calculators

Confidence Interval CalculatorCalculate the confidence interval for a sample mean.Sample Size CalculatorCalculate the minimum sample size needed for a survey or study at a given confidence level and margin of error.Margin of Error CalculatorCalculate the margin of error for a survey result given sample size and confidence level.Correlation Coefficient CalculatorCalculate the Pearson correlation coefficient between two paired sets of numbers.

Conclusion

Because it's unitless, the coefficient of variation lets you ask which of two datasets is more variable relative to its own scale, in a way raw standard deviation cannot answer on its own. Use it alongside the mean and standard deviation this calculator reports, not as a replacement for looking at the underlying numbers.