Calculadora de Frequência Alélica
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
p = (2·AA + Aa) / 2N; q = 1 − p; HWE: AA=p², Aa=2pq, aa=q²
About this calculator
The Allele Frequency Calculator determines the frequencies of alleles A and a in a population from genotype counts. It uses Hardy-Weinberg principle formulas: p (frequency of A) is calculated as (2 times the number of AA homozygotes plus the number of Aa heterozygotes) divided by 2 times the total individuals. The frequency of a (q) is simply 1 minus p. The tool also displays expected genotype frequencies under Hardy-Weinberg equilibrium (AA = p², Aa = 2pq, aa = q²).
This calculator is useful for genetics students, biologists, and researchers analyzing genetic variation in populations. For example, when studying the distribution of a hereditary disease, one can check if the population is in Hardy-Weinberg equilibrium. The tool also helps detect deviations that may indicate natural selection, genetic drift, or gene flow.
Important caveats: the formula assumes a large population with random mating, no mutation, migration, or selection. In small populations or with non-random mating, results may not reflect reality. Also, ensure that genotype counts sum to the total number of individuals correctly; input errors can lead to inconsistent frequencies.
Frequently asked questions
What is the Hardy-Weinberg principle?
It is a model that describes how allele and genotype frequencies remain constant in an ideal population over generations in the absence of evolutionary forces.
How do I interpret the expected genotype frequency results?
The expected frequencies (p², 2pq, q²) are what would be observed if the population were in Hardy-Weinberg equilibrium. Compare them with observed frequencies to detect deviations.
Can I use this calculator for more than two alleles?
No, this calculator is specific for a locus with two alleles (A and a). For multiple alleles, other tools are needed.
What does it mean if observed frequencies differ from expected?
It may indicate that the population is not in equilibrium, due to factors such as natural selection, genetic drift, migration, mutation, or non-random mating.
Do I need to enter absolute numbers or percentages?
Enter absolute numbers of individuals (counts). The calculator automatically converts to frequencies.