Hardy-Weinberg Equilibrium Calculator

Analyze genotype distributions. Enter either allele frequencies or observed genotype counts to determine expected distributions and test for equilibrium using a Chi-Square test.

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Input Mode Selection

Select how you want to input your data.

Allele Frequencies

Dominant Allele Frequency (p)

Recessive Allele Frequency (q)

Equilibrium Distribution

Calculated p / q 0.600 / 0.400

f(AA) = p² 0.360 (36.0%)

f(Aa) = 2pq 0.480 (48.0%)

f(aa) = q² 0.160 (16.0%)

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Chi-Square Interpretation

If Chi-Square exceeds 3.841 (df = 1, α = 0.05), the population deviates significantly from equilibrium due to evolutionary mechanisms.

Hardy-Weinberg Expected Genotype Frequency Reference Table

p (Dominant Allele)	q (Recessive Allele)	p² (AA %)	2pq (Aa %)	q² (aa %)
0.90	0.10	81.0%	18.0%	1.0%
0.70	0.30	49.0%	42.0%	9.0%
0.50	0.50	25.0%	50.0%	25.0%
0.30	0.70	9.0%	42.0%	49.0%
0.10	0.90	1.0%	18.0%	81.0%

Calculation Methodology & Biological Principles

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Hardy-Weinberg Equations

p + q = 1 p² + 2pq + q² = 1 Chi-Square (χ²) = Σ [(Observed - Expected)² / Expected]

The binomial expansion represents random gamete fertilization in ideal populations.

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Population Assumptions

1. No mutation
2. Random mating
3. No natural selection
4. Infinite population size
5. No gene flow or migration

Frequently Asked Questions

What is Hardy-Weinberg Equilibrium? ▼

Hardy-Weinberg equilibrium is a fundamental principle of population genetics stating that allele and genotype frequencies in a population remain constant from generation to generation in the absence of evolutionary influences.

What are the 5 Hardy-Weinberg conditions? ▼

The 5 necessary conditions for equilibrium are: 1) No mutation, 2) Random mating, 3) No natural selection, 4) An infinitely large population size (no genetic drift), and 5) No gene flow/migration.

What does a Chi-Square test tell you about Hardy-Weinberg equilibrium? ▼

A Chi-Square test compares observed genotype counts from a population sample with expected counts derived from p^2, 2pq, and q^2. A Chi-Square statistic greater than 3.841 (df = 1, alpha = 0.05) indicates significant deviation from equilibrium.