Fisher Skewness

$$\gamma_1 = {\mu_3\over {\mu_2}^{3/2}} = {\mu_3\over \sigma^3},$$

where $\mu_i$ is the $i$ Moment about the Mean, and $\sigma=\sqrt{\mu_2}$ is the Standard Deviation.

See also Fisher Kurtosis, Moment, Skewness, Standard Deviation