Skewness Calculator

This skewness calculator measures the asymmetry of a data set. Enter your numbers and the calculator returns the moment coefficient of skewness, along with the mean and the sample size. Skewness tells you which way a distribution leans: a positive value means a long tail to the right (a few large values), a negative value means a long tail to the left, and zero means it is symmetric, like the normal distribution. Knowing the skewness helps you decide whether the mean is a fair summary or whether the median would be better. The formula, a worked example and the assumptions are below.

Data set, comma separated

Mean

Sample size

The formula

The moment coefficient of skewness is the third standardised moment: the average of (x minus the mean) cubed, divided by the standard deviation cubed (using the population standard deviation). Positive means right-skewed, negative left-skewed, zero symmetric.

Worked example

The symmetric set 2, 4, 6, 8, 10 has mean 6 and a skewness of 0, because the values balance evenly either side of the mean. Enter that set to confirm, then try an asymmetric one.

Frequently asked questions

What does skewness measure?

The asymmetry of a distribution. Positive skew has a long right tail, negative skew a long left tail.

What does zero skewness mean?

A symmetric distribution, where values are balanced either side of the mean, like the normal distribution.

Why does skewness matter?

It tells you whether the mean is pulled by a tail, and whether the median might describe the centre better.

Who this calculator is for

This calculator is for statistics students, researchers and analysts.

What this calculator assumes

You enter valid numbers.
The standard formula is applied.
Results are rounded for display.

Formula and sources

Related calculators

Standard Deviation Calculator: spread of data.
Z-Score Calculator: standard score.
Mean Median Mode Calculator: averages.

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