What is the Hardy-Weinberg equilibrium?

The Hardy-Weinberg equilibrium is a principle stating that both allele and genotype frequencies in a population remain constant from generation to generation in the absence of evolutionary influences. It provides a baseline to detect evolution.

How do I use this calculator?

Enter the allele frequency p (as a fraction between 0 and 1) for one allele. The calculator then computes expected genotype frequencies: p² for homozygous dominant, 2pq for heterozygous, and q² for homozygous recessive, where q = 1 - p.

What assumptions does the Hardy-Weinberg model make?

The model assumes a large population, random mating, no mutation, no migration, and no natural selection. If actual genotype frequencies differ from expected, it suggests one or more of these assumptions are violated.

Biologie et sciences de la vie

Instantané, privé et gratuit

Hardy-Weinberg Equilibrium Calculator.

Calculate expected genotype frequencies from allele frequency p under the Hardy-Weinberg model.

Calcul sur l'appareilSans inscription

Saisissez vos valeurs

Les résultats se mettent à jour pendant la saisie.

02 / RÉPONSE

Allele frequency p

alleleP

0,5

Allele frequency q

0,5

Homozygous dominant (p²)

0,25

Heterozygous (2pq)

0,5

Homozygous recessive (q²)

0,25

Total frequency

Educational arithmetic only. The Hardy-Weinberg and qPCR outputs use the explicitly stated mathematical models; they do not infer experimental, clinical, or veterinary recommendations.

Use Cases

Population Genetics Education

Helps students and educators quickly compute expected genotype frequencies to illustrate Hardy-Weinberg principles and test for evolutionary influences.

Example: If p = 0.6, expected frequencies are p² = 0.36, 2pq = 0.48, q² = 0.16.

Research Data Comparison

Researchers can compare observed genotype frequencies from field data to expected frequencies to assess if a population is in equilibrium.

Example: Compare observed counts to expected from p to detect selection or non-random mating.

Frequently Asked Questions

What is the Hardy-Weinberg equilibrium?: The Hardy-Weinberg equilibrium is a principle stating that both allele and genotype frequencies in a population remain constant from generation to generation in the absence of evolutionary influences. It provides a baseline to detect evolution.
How do I use this calculator?: Enter the allele frequency p (as a fraction between 0 and 1) for one allele. The calculator then computes expected genotype frequencies: p² for homozygous dominant, 2pq for heterozygous, and q² for homozygous recessive, where q = 1 - p.
What assumptions does the Hardy-Weinberg model make?: The model assumes a large population, random mating, no mutation, no migration, and no natural selection. If actual genotype frequencies differ from expected, it suggests one or more of these assumptions are violated.

Tips & Common Mistakes

Tips

Ensure the allele frequency p is entered as a fraction between 0 and 1 (e.g., 0.3 for 30%).
Remember that q = 1 - p, so if p is 0.7, q is 0.3.
Use the expected frequencies to check if a population is evolving by comparing to observed data.
For a quick check, the sum of p² + 2pq + q² should always equal 1.

Common Mistakes to Avoid

Entering p as a percentage (e.g., 30) instead of a fraction (0.3).
Forgetting that p and q must sum to 1, so q is not entered but derived.
Misinterpreting the output: p² is the frequency of homozygous dominant genotype, not the allele frequency.

Last updated: August 13, 2026