Coefficient of Variation Calculator

This calculator finds the coefficient of variation of a data set, a measure of relative variability that lets you compare the spread of different data on a level footing. The standard deviation tells you how spread out data is, but its size depends on the scale of the numbers, so it is hard to compare the variability of, say, house prices against rainfall, or a process measured in millimetres against one measured in kilograms. The coefficient of variation, also called the relative standard deviation, solves this by expressing the standard deviation as a percentage of the mean. Because it is a ratio, it has no units, so it allows a fair comparison of variability between data sets of completely different scales or units. A higher coefficient of variation means more relative spread; a lower one means the data clusters more tightly around its average. It is widely used in finance to compare the risk of investments, in laboratory science to judge the precision and repeatability of measurements, and in quality control. This tool computes it. You paste or type your numbers, and the calculator returns the coefficient of variation as a percentage, along with the mean and the standard deviation it is based on, and the population version for comparison. The results update as you edit the data. Use it to compare variability across different measures, to assess investment risk relative to return, to check measurement precision, or for statistics study. A practical note: the coefficient of variation is most meaningful for data measured on a ratio scale with a true zero and positive values, such as prices, weights or counts, and it becomes unreliable when the mean is close to zero, since dividing by a tiny mean inflates the result.

Coefficient of variation = standard deviation / mean x 100. Unitless, so it compares spread across different scales. Unreliable when the mean is near zero.