Allele Frequency Calculator
Determine allele frequencies, genotype proportions, and Hardy–Weinberg equilibrium values using genotype count data.
Genotype-Based Allele Frequency Computation
Allele frequency needs a defined population and valid counts
Allele frequency is the proportion of copies of an allele among all copies of the gene in the population sample being studied. For a two-allele locus in a diploid sample with genotype counts AA, Aa, and aa, the A frequency is (2×AA + Aa) ÷ (2×(AA + Aa + aa)). This assumes each sampled individual contributes two copies and the genotype classifications are mutually exclusive.
For example, suppose 20 sampled individuals have AA, 50 have Aa, and 30 have aa. The sample contains 200 copies of the locus, including 90 copies of allele A, so its estimated frequency is 0.45. The other allele is 0.55 in this simplified two-allele case. Missing genotype calls or a different ploidy level require a different denominator.
A frequency estimate is descriptive; it does not by itself demonstrate Hardy–Weinberg equilibrium, selection, ancestry, or a causal effect. Small or unrepresentative samples can give unstable estimates, and genotyping error can distort both numerator and denominator. Report sample size and the assumptions alongside the result.