Hardy-Weinberg 2pq
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The Hardy-Weinberg 2pq calculator determines the heterozygous genotype (Aa) frequency in a population under Hardy-Weinberg equilibrium. It uses allele frequencies p and q, where p² represents AA, 2pq represents Aa, and q² represents aa. This applies to two-allele genes in ideal populations without selection, mutation, or gene flow.
To use the calculator, input the dominant (p) and recessive (q) allele frequencies. The 2pq result shows the expected heterozygote proportion. It's commonly used in genetics to compare observed data with theoretical expectations, identifying evolutionary influences like selection or migration.
Cautions: the model assumes random mating, sexual reproduction, and no disruptive factors. Real populations may deviate due to inbreeding, migration, or mutations. p and q values must be calculated first, typically by taking the square root of the homozygous recessive genotype frequency (q²).
Frequently asked questions
What is allele frequency?
It is the proportion of a specific allele in relation to all alleles at a given locus in a population.
Do I need all genotype frequencies to use this calculator?
No, only the allele frequencies p and q are required to calculate 2pq.
What is the purpose of Hardy-Weinberg equilibrium?
It serves as a theoretical model to predict genotypes in non-evolving populations and detect evolutionary factors causing deviations.
How do I find p if I know q?
Since p + q = 1, subtract q from 1 to obtain p.