Hardy-Weinberg Equilibrium Calculator

How to Use This Calculator

1. Enter the dominant allele frequency p (0 to 1). q = 1 − p is calculated automatically.
2. Results show p², 2pq, and q² genotype frequencies.
3. Use From Phenotype Freq to back-calculate p and q from observable recessive phenotype frequency.
4. Use Test for Equilibrium to run a chi-square test on observed genotype counts.

Formula

Example

Frequently Asked Questions

• What is the Hardy-Weinberg principle? ▼
  The Hardy-Weinberg principle states that allele and genotype frequencies in a population remain constant from generation to generation in the absence of other evolutionary influences. The equation p² + 2pq + q² = 1 describes genotype frequencies.
• What are the 5 conditions for Hardy-Weinberg equilibrium? ▼
  HWE requires: (1) no mutations, (2) no gene flow/migration, (3) no natural selection, (4) random mating (no sexual selection), and (5) large population size (no genetic drift). Violation of any condition can shift allele frequencies.
• How do I find allele frequency from phenotype frequency? ▼
  If the recessive phenotype frequency is q², then q = √(q²) and p = 1 − q. This assumes the population is in HWE and the trait shows simple dominant-recessive inheritance.
• What is the inbreeding coefficient F? ▼
  F measures the probability that two alleles in an individual are identical by descent. F = 0 means random mating (HWE). F = 1 means complete inbreeding. Inbreeding increases homozygosity and reduces heterozygosity.
• How do you test if a population is in Hardy-Weinberg equilibrium? ▼
  Use a chi-square goodness-of-fit test. Compare observed genotype counts with expected counts from HWE frequencies. A chi-square value above 3.84 (1 df, α = 0.05) indicates significant deviation from HWE.

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