A number indicative of column performance when resolution is taken into account: \[N=\frac{16\ R_{\text{s}}^{2}}{(1- \alpha )^{2}}\] where R s is the peak resolution and α is the separation factor.
See also: plate number (in chromatography)
Source:
Orange Book, 2nd ed., p. 108 (https://media.iupac.org/publications/analytical_compendium/)