A calculation is presented that converts plant frequency per plot size sampled to expected frequency per any plot size of interest so as to compare studies that used different plot sizes or to assess degrees of spatial randomness in individual studies that used multiple plot sizes. Expected frequency is exponentially related to measured frequency, being dependent on plot size of interest relative to plot size from which measured frequency was obtained. Expected frequency per plot size of interest (F_e) may be expressed as F_e  =  1 − (1 − F_s)^r, where F_s is measured frequency per plot size sampled and r is the ratio of plot size of interest to plot size sampled. The calculation assumes that plants are randomly distributed, or approximately so, and criteria for presence of plants in plots are consistent in studies being compared.