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Hardy-Weinberg Equilibrium Calculator.

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

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Set your values

Results update as you type.

alleleP: 0.5

alleleP

0.500000
Allele frequency q: 0.5

Allele frequency q

0.500000
Homozygous dominant (p²): 0.25

Homozygous dominant (p²)

0.250000
Heterozygous (2pq): 0.5

Heterozygous (2pq)

0.500000
Homozygous recessive (q²): 0.25

Homozygous recessive (q²)

0.250000
Total frequency: 1

Total frequency

1.0000

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