Hardy-Weinberg Equilibrium Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026A baseline for detecting evolution
The Hardy-Weinberg principle predicts genotype frequencies in a population that is NOT evolving - no selection, mutation, migration, genetic drift, or non-random mating - serving as a null model that lets biologists detect when evolution actually is occurring.
Worked example
For an allele frequency p of 0.7 (so q = 0.3):
AA = 0.7² = 0.49, Aa = 2 x 0.7 x 0.3 = 0.42, aa = 0.3² = 0.09
Notice these three genotype frequencies sum to exactly 1.0 (0.49 + 0.42 + 0.09) - a useful check that the calculation is correct, since p^2 + 2pq + q^2 = (p+q)^2 = 1^2 = 1 by definition whenever p and q are the only two alleles present.
When a real population's observed genotype frequencies deviate significantly from these predicted equilibrium values, it signals that one or more evolutionary forces are actively acting on that population.