Enter genotype counts to calculate p, q, and expected heterozygosity for a two-allele population.
p = (2AA + Aa) / 2N; q = (2aa + Aa) / 2NAllele frequency counts how often each allele appears in the population's gene copies. Homozygotes contribute two copies of the same allele, while heterozygotes contribute one copy of each allele.
| Symbol | Variable | Description |
|---|---|---|
| AA | Dominant homozygotes | Individuals with two dominant alleles. |
| Aa | Heterozygotes | Individuals with one dominant and one recessive allele. |
| aa | Recessive homozygotes | Individuals with two recessive alleles. |
| N | Total individuals | AA + Aa + aa. |
Enter genotype counts
Count individuals in each genotype class: AA, Aa, and aa.
Calculate p and q
The calculator converts genotype counts into allele frequencies for the dominant and recessive alleles.
Review heterozygosity
Expected heterozygosity, 2pq, is useful for Hardy-Weinberg checks and population-genetics interpretation.
Suppose a sample has 49 AA, 42 Aa, and 9 aa individuals. There are 100 individuals and 200 total allele copies. The dominant allele count is 2×49 + 42 = 140, so p = 0.70. The recessive allele frequency is q = 0.30.
Allele frequency describes copies of alleles in the population, while genotype frequency describes individuals with each genotype. The two are related, but they are not the same measurement.
Natural Selection Simulation Calculator
Simulate allele frequency change across generations from initial p and genotype fitness values for AA, Aa, and aa.
Genetic Drift Calculator
Estimate drift variance, allele frequency range, heterozygosity retention, fixation probability, and loss probability in a finite effective population.
Hardy-Weinberg Calculator
Calculate allele and genotype frequencies for a population in genetic equilibrium.