Biology
Hardy-Weinberg Genotype Rate Calculator
Calculate Hardy-Weinberg allele and genotype rates, expected counts, observed allele frequency, and a future heterozygote reference.
Allele q frequency-
Expected p-p rate-
Expected p-q rate-
Expected q-q rate-
Expected p-p count-
Expected p-q count-
Expected q-q count-
Observed genotype total-
Observed p allele frequency-
Future heterozygote reference-
Entered p minus calculated observed p-
Decision view
Hardy-Weinberg genotype composition
Hardy-Weinberg genotype compositionThe p-squared, two-p-q, and q-squared shares close to one whole, with expected counts and observed p kept separate.
Exact scenario comparisonAllele p frequency changes while all other entered assumptions remain constant.
| Allele p frequency | Allele q frequency | Expected p-p rate | Expected p-q rate | Expected q-q rate | Expected p-p count | Expected p-q count | Expected q-q count | Observed genotype total | Observed p allele frequency | Future heterozygote reference | Entered p minus calculated observed p |
|---|
How to use Hardy-Weinberg Genotype Rate Calculator
- Enter allele p and population size.
- Enter observed genotype counts separately.
- Add a comparison p and future population only for the labeled references.
- Compare the expected composition with the observed-frequency result.
Calculator guide
Understanding Hardy-Weinberg Genotype Rate Calculator
Hardy-Weinberg arithmetic expands the two allele frequencies p and q into three expected genotype proportions. This page also reconstructs p from entered genotype observations so the expected composition and observed allele count remain separate and auditable.
Calculation method
How the calculation works
Apply p plus q equals one and the p-squared, two-p-q, q-squared expansion, while keeping entered observations and implied allele frequency auditable. Expected rates close to one, while observed allele frequency uses only the entered nonempty genotype sample. Set q equal to one minus p, expand (p+q)², multiply each genotype rate by population size, and count observed p alleles from genotype observations.
Detailed calculation process
Expand allele frequencies into expected genotype composition
The default p frequency is 0.62 in a population of 1,200, with observed counts 470 p-p, 570 p-q, and 160 q-q.
General formula: q = 1-pf(pp) = p^2f(pq) = 2pqf(qq) = q^2E_g = Nf(g)p_obs = [2O_pp + O_pq]/[2(O_pp + O_pq + O_qq)] The binomial expansion produces mutually exclusive expected genotype shares that sum to one. Multiplying by N produces expected counts, while the separate observed-frequency equation counts two p alleles in p-p and one in p-q.
What each symbol means
Worked substitution with the default inputs
The defaults imply q = 0.38 and expected shares of 38.44% p-p, 47.12% p-q, and 14.44% q-q; the observed p frequency is 0.62917.
Genotype composition
See p², 2pq, and q² close to one whole
A stacked composition bar and expected-count labels show how the entered allele frequency partitions the population.
Worked situations
Practical examples
- At p = 0.62, q equals 0.38.
- Expected heterozygotes are 565.44 in a population of 1,200.
- The entered observations imply p = 0.62917.
Better inputs
Useful tips
- Keep expected and observed quantities clearly separated.
- Use counts from the same sampled population.
- Assess equilibrium with an appropriate statistical test rather than visual similarity alone.
Before relying on the result
Limitations and common mistakes
- Hardy-Weinberg expectations assume random mating, a large population, and no selection, mutation, migration, or genotyping error.
- Expected counts are not proof that a population is in equilibrium.
- The page models one two-allele locus.
Reference
Key terms
- Allele frequency
- Share of allele copies represented by p or q.
- Heterozygote
- An individual carrying one p and one q allele.
- Expected count
- Population size multiplied by an expected genotype proportion.
- Observed p frequency
- p alleles counted directly from entered genotype observations.
Important note
Calculated from the entered values using the displayed biological or statistical model. Study design, sampling, measurement quality, and biological variation affect interpretation.
Frequently asked questions
Why is the heterozygote term 2pq?
There are two allele-order combinations: p from one parent and q from the other, or the reverse.
Can expected counts be fractional?
Yes. They are population-size-scaled expectations, not observed individuals.
Do expected rates prove equilibrium?
No. Statistical comparison and model assumptions must also be considered.
Why might observed p differ from entered p?
The entered genotype counts may imply a different allele composition.