Calculate Hardy-Weinberg equilibrium from AA, Aa, and aa counts, showing allele frequencies, expected genotype counts, and chi-square.

HWE Calculator

Enter genotype counts (AA, Aa, and aa):

Calculation Steps

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HWE Formulas

For a single bi-allelic locus with allele frequencies p and q (where p + q = 1), Hardyโ€“Weinberg equilibrium (HWE) predicts the following expected genotype frequencies:

p + q & = 1 \ f(AA) & = pยฒ \ f(Aa) & = 2pq \ f(aa) & = qยฒ

Variables:

  • p is the frequency of the first allele (A) in the population
  • q is the frequency of the second allele (a) in the population
  • pยฒ, 2pq, and qยฒ are the expected genotype frequencies of AA, Aa, and aa, respectively

If you have a sample size of N individuals, the expected genotype counts under HWE are E(AA)=pยฒยทN, E(Aa)=2pqยทN, and E(aa)=qยฒยทN.

How to Calculate HWE Expected Genotype Frequencies?

The following steps outline how to calculate the Hardyโ€“Weinberg expected genotype frequencies using f(AA)=pยฒ, f(Aa)=2pq, and f(aa)=qยฒ (with p + q = 1).

  1. Determine the frequency of the first allele in the population (p).
  2. Compute the frequency of the second allele as q = 1 โˆ’ p.
  3. Calculate the expected genotype frequencies: pยฒ (AA), 2pq (Aa), and qยฒ (aa).
  4. If you have a total sample size N, multiply each expected frequency by N to obtain expected genotype counts.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Frequency of the first allele in the population (p) = 0.6

Frequency of the second allele in the population (q) = 0.4

Expected genotype frequencies under HWE: pยฒ = 0.36 (AA), 2pq = 0.48 (Aa), and qยฒ = 0.16 (aa).