About the Coefficient of Variation Calculator
The coefficient of variation, often called CV or relative standard deviation, shows how big the spread of a data set is compared with its average. It is the standard deviation divided by the mean, written as a percentage. Because it has no unit, it lets you compare the variability of things measured in different units or at different scales. Paste your numbers and choose whether they are a sample or the whole population. Type your numbers, separated by commas, spaces or lines and the coefficient of variation appears at once, with a few related figures underneath, and you can copy the result with one tap. The sums run in your browser, so nothing you enter is uploaded.
Updated October 2026
How to use the Coefficient of Variation Calculator
- 1Enter your numbers, separated by commas, spaces or lines.
- 2Pick the units or options from the menus if the coefficient of variation tool offers them.
- 3Read the coefficient of variation in the large result box.
- 4Look at the extra rows for related figures.
- 5Press Copy result to keep the answer.
When you need the coefficient of variation
Lab scientists use CV to judge how repeatable a measurement is: a CV under 5 percent is often called good. Finance people use it to compare the risk per unit of return of two investments, and quality teams use it to compare machines.
The key advantage is that it compares apples with oranges. A set of heights in centimetres with a standard deviation of 7 and a set of weights in kilograms with a standard deviation of 12 cannot be compared directly, but their CVs can.
How the coefficient of variation is worked out
CV = standard deviation ÷ |mean| × 100%. The standard deviation divides by n − 1 for a sample and by n for a whole population. For the numbers 12, 15, 11, 14, 18, 13 and 16, the mean is 14.14 and the sample standard deviation is 2.41, so the CV is 2.41 ÷ 14.14 × 100 = 17.04%. Treated as a whole population the standard deviation is 2.23 and the CV is 15.8%.
Every answer on this page comes from that one rule, so you can check any result by hand with a calculator. The figures shown underneath, such as other units, are conversions of the same answer.
- Sample or population
- Shows mean and standard deviation
- Any number of values
Mistakes to avoid with coefficient of variation
The CV is meaningless when the mean is near zero, because the division blows up, and it is not defined for a mean of exactly zero. It also assumes values on a ratio scale, such as lengths or amounts, not temperatures in Celsius, where zero is arbitrary.
On phone and computer
On a phone, type into the boxes one after another and read the coefficient of variation underneath; Copy result puts it on the clipboard for a message or a note. On a computer the inputs sit on the left and the answer on the right, so you can change one figure and watch the coefficient of variation move. The coefficient of variation calculator works the same on both. The coefficient is a ratio of two other measures, so find them with Standard Deviation Calculator and Average Calculator. Variance Calculator shows the spread before the square root, and Standard Error Calculator measures the accuracy of the mean.
Features
- Needs a non-zero mean
- Ratio scale data only
- Compare CVs, not standard deviations
- Clear messages when the coefficient of variation inputs make no sense
- Copy the result with one tap
- Private: nothing is uploaded
Frequently asked questions
How do I calculate coefficient of variation?
CV = standard deviation ÷ |mean| × 100%. The standard deviation divides by n − 1 for a sample and by n for a whole population. For the numbers 12, 15, 11, 14, 18, 13 and 16, the mean is 14.14 and the sample standard deviation is 2.41, so the CV is 2.41 ÷ 14.14 × 100 = 17.04%. Treated as a whole population the standard deviation is 2.23 and the CV is 15.8%.
What is the formula for coefficient of variation?
CV = standard deviation ÷ |mean| × 100%. The standard deviation divides by n − 1 for a sample and by n for a whole population. The coefficient of variation calculator applies it exactly and rounds only the displayed answer to six significant figures.
What is a good CV?
It depends on the field. In many labs under 10 percent is acceptable and under 5 percent excellent, but natural data such as incomes can be far higher.
Sample or population?
Choose sample if your numbers are a subset of a larger group, which is the usual case, and population if you have every value.
Why can't I use zero or negative means?
With a mean of zero the ratio is undefined, and a mean near zero gives huge, unstable values.
Is this coefficient of variation calculator free and private?
Yes. It is free, needs no account and runs in your browser, so the numbers you type are not uploaded or stored.