Calculate expected genotype frequencies (AA, Aa, aa) in a population using Hardy-Weinberg equilibrium principles. Input allele frequencies or genotype counts to determine population genetics distributions.
AA Genotype Frequency
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Aa Genotype Frequency
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aa Genotype Frequency
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Allele A Frequency (p)
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Allele a Frequency (q)
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Total Population
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Hardy-Weinberg equilibrium states that allele and genotype frequencies remain constant in a population from generation to generation, provided certain conditions are met (no mutations, no selection, no migration, large population size, and random mating).
If p is the frequency of allele A and q is the frequency of allele a, then the genotype frequencies are: AA = p², Aa = 2pq, and aa = q². Remember that p + q = 1.
If p + q doesn't equal 1, there may be an error in your data entry or the population may have more than two alleles at this locus. In a two-allele system, the frequencies must sum to 1.
To find p: count all A alleles (2×AA + Aa) and divide by total alleles (2×N). To find q: count all a alleles (2×aa + Aa) and divide by total alleles (2×N), where N is the total number of individuals.
Homozygous genotypes have two identical alleles (AA or aa), while heterozygous genotypes have two different alleles (Aa). Homozygous dominant is AA, homozygous recessive is aa.
This calculator shows expected frequencies under Hardy-Weinberg conditions. Real populations may deviate due to factors like inbreeding, population structure, or natural selection, but it provides a useful baseline for comparison.
Larger sample sizes provide more accurate estimates. Generally, you want at least 30-50 individuals for basic calculations, though hundreds or thousands give more reliable results for population genetics studies.
Frequencies range from 0 to 1, where 1 means 100% of the population has that genotype. The three genotype frequencies (AA, Aa, aa) should always sum to 1.0 in a complete analysis.