Hardy-Weinberg Calculator
Calculate Hardy-Weinberg allele and genotype frequencies from counts, then run a chi-square goodness-of-fit test with degrees of freedom, an exact p-value, and a reject or fail-to-reject verdict.
At a glance
- Computes
- Allele and genotype frequencies, plus a chi-square goodness-of-fit test with df and p.
- You supply
- Observed genotype counts, or an allele frequency, for one two-allele locus.
- Use when
- One locus, two alleles, and you need to test a population against equilibrium.
- Assumes
- Random mating, no selection, migration, mutation, or drift, and a large population.
Genotype frequency against Allele frequency p
Allele frequencies
Enter values
Biallelic autosomal Hardy-Weinberg model.
- p allele frequency
- 0
- q allele frequency
- 0
- Chi-square
- Only for counts
- Degrees of freedom
- Only for counts
- p-value
- Only for counts
- Verdict
- Only for counts
Chi-square is a classroom check, not proof of equilibrium.
| Genotype | Frequency | Percent | Expected count | Observed count |
|---|
Equilibrium assumptions
- Biallelic diploid autosomal locus.
- Random mating in a large population.
- No selection, mutation, migration, or genetic drift.
- Equal allele frequencies across sexes.
p + q = 1; AA = p^2; Aa = 2pq; aa = q^2
How?
How this is calculated
In allele-frequency mode, the calculator accepts p, q, or both. In recessive phenotype mode, it takes the square root of q squared to estimate q and then sets p to 1 minus q.
In genotype-count mode, p is estimated as twice AA plus Aa divided by twice the sample size. Expected counts are the Hardy-Weinberg genotype frequencies multiplied by that sample size. The chi-square value sums observed minus expected squared over expected across AA, Aa, and aa.
Formula: p + q = 1; AA = p^2; Aa = 2pq; aa = q^2
Sources
- Hardy-Weinberg principle. Wikipedia. Retrieved .
- Chi-Square Test of Goodness-of-Fit (Hardy-Weinberg df). Biology LibreTexts. Retrieved .
- A straightforward multiallelic significance test for the Hardy-Weinberg equilibrium law. Genetics and Molecular Biology 32(3):619-625 (Lauretto et al., 2009). Retrieved .
Method last reviewed