Hardy–Weinberg Calculator

About this calculator

This calculator finds expected genotype frequencies from an allele frequency under the Hardy–Weinberg principle: for a gene with two alleles at frequencies p and q (where p + q = 1), the genotype frequencies in a population at equilibrium are p² (homozygous dominant), 2pq (heterozygous), and q² (homozygous recessive) — the expansion of (p + q)².

Population geneticists use this as a null-hypothesis baseline: real populations are compared against Hardy–Weinberg expectations to detect evolutionary forces like natural selection, genetic drift, non-random mating, or migration, since a population only stays in equilibrium absent these pressures. It's taught in every introductory genetics course as the foundation of population genetics. Enter an allele frequency (p) to get the expected genotype frequencies.