Hardy-Weinberg Equilibrium

Interactive calculator for allele and genotype frequencies in populations

Allele Frequencies

Frequency of A allele (p)

Frequency of a allele (q)0.400

q = 1 - p

p + q = 1.000✓

Genotype Frequencies

AA (p²)0.360 (36.0%)

Aa (2pq)0.480 (48.0%)

aa (q²)0.160 (16.0%)

p² + 2pq + q² = 1.000✓

Population Parameters

Enable Genetic Drift

Selection Coefficient (s)0.00

Selection against aa genotype (0 = no selection, 1 = lethal)

Simulation Controls

Generation

Hardy-Weinberg Principle

Core Principle: In a large, randomly mating population with no evolutionary forces acting upon it, allele and genotype frequencies remain constant from generation to generation.

The Equations:

p + q = 1

p² + 2pq + q² = 1

where p = frequency of dominant allele (A), q = frequency of recessive allele (a)

Five Assumptions (Equilibrium Conditions):

No mutations: Alleles don't change from one form to another
Random mating: Individuals pair by chance, not according to genotype
No gene flow: No migration in or out of the population
Infinite population size: No genetic drift (random sampling error)
No selection: All genotypes have equal fitness

Example:

In a population, 16% of individuals have the recessive phenotype (aa). What percentage are heterozygous carriers (Aa)?

Solution: q² = 0.16, so q = 0.4 and p = 0.6. Heterozygotes (2pq) = 2(0.6)(0.4) = 0.48 or 48%