Skewness Calculator
Measure the asymmetry of your data with the sample and population skewness — plus excess kurtosis — and see how the mean and median line up on the distribution.
- Population skewness
- 1.6235
- Excess kurtosis (sample)
- 3.6605
- Mean (x̄)
- 5.3000
- Median
- 4.0000
Distribution
n = 10When the mean sits to the right of the median, the distribution is typically right-skewed; to the left, left-skewed.
How to use this calculator
- Enter your numbers, separated by commas, spaces, or new lines.
- Read the sample skewness at the top with a plain-language interpretation.
- The chart marks the mean and median so you can see the direction of the skew.
What is skewness?
Skewness measures the asymmetry of a distribution around its mean. A skewness of zero means the data is symmetric. Positive skewness (right skew) means a longer tail on the right; negative skewness (left skew) means a longer tail on the left.
- Positive / right skew — mean is usually greater than the median; long right tail.
- Negative / left skew — mean is usually less than the median; long left tail.
- Zero skew — symmetric, like the normal distribution.
Skewness formula
The population skewness (the Fisher–Pearson coefficient) is:
The sample skewness applies an adjustment for bias (this is what Excel’s SKEW returns):
How to interpret skewness
A common rule of thumb: skewness between −0.5 and 0.5 is fairly symmetric, between 0.5 and 1 (or −0.5 and −1) is moderately skewed, and beyond ±1 is highly skewed. The sign tells you the direction of the longer tail.
Comparing the mean and median is a quick check: a mean noticeably greater than the median suggests right skew, and a mean below the median suggests left skew.Skewness in Excel
Use =SKEW(range) for the sample skewness (the bias-adjusted G₁), or =SKEW.P(range) for the population skewness. Excel’s =KURT(range) returns the sample excess kurtosis.
Frequently asked questions
What does negative skew mean?
Negative skew (left skew) means the distribution has a longer tail on the left side. The bulk of the values are concentrated on the right, and the mean is typically pulled below the median by the low outliers.
What is the difference between sample and population skewness?
Population skewness (g₁) uses the population moments directly, while sample skewness (G₁) applies a correction factor of n / [(n−1)(n−2)] to reduce bias when estimating skewness from a sample. Excel’s SKEW function returns the sample value.
What is considered a highly skewed distribution?
As a rough guideline, a skewness beyond +1 or below −1 indicates a highly skewed distribution, values between ±0.5 and ±1 indicate moderate skew, and values within ±0.5 are considered fairly symmetric.
How do I calculate skewness in Excel?
Use =SKEW(range) for the bias-adjusted sample skewness or =SKEW.P(range) for the population skewness.