Skewness Calculator
Measure the asymmetry of a distribution.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Enter at least 3 values separated by commas or spaces. The calculator uses the adjusted Fisher-Pearson standardized moment coefficient to compute skewness. It also provides an interpretation: values near zero indicate symmetry, positive values indicate a right tail, and negative values indicate a left tail.
About Skewness
Skewness quantifies how asymmetric a distribution is. A perfectly symmetric distribution (like the normal curve) has skewness of zero. Positive (right) skew means the right tail is longer, with more extreme high values. Negative (left) skew means the left tail is longer. Income distributions typically show positive skew. Skewness helps determine which statistical methods are appropriate, as many tests assume approximate symmetry.
Frequently Asked Questions
What skewness values indicate significant asymmetry?
Generally, absolute skewness below 0.5 is approximately symmetric, 0.5 to 1.0 is moderately skewed, and above 1.0 is highly skewed. These thresholds are guidelines, not strict rules.
How does skewness affect the mean vs median?
In right-skewed distributions, the mean is typically greater than the median because extreme high values pull the mean up. In left-skewed distributions, the mean is typically less than the median.
Why do I need at least 3 data points?
The adjusted Fisher-Pearson formula requires n >= 3 because the correction factor includes n-1 and n-2 in the denominator. With fewer points, the calculation is undefined.