Hardy-Weinberg Carrier Frequency Calculator
Allele frequencies, carrier frequency and genotype proportions from the frequency of the recessive phenotype.
Results
What this tool does
The counter-intuitive result of the Hardy-Weinberg principle is how many unaffected carriers a rare recessive condition implies. If one person in twenty-five shows the recessive trait, one in three carries the allele without knowing it — and the rarer the condition, the larger the ratio of carriers to affected people becomes. Enter the frequency of the recessive phenotype as a decimal, so 1 in 2500 is 0.0004.
Formula
p + q = 1 ; p² + 2pq + q² = 1
Variables
| Symbol | Meaning | Unit |
|---|---|---|
q2 | Frequency of the recessive phenotype | — |
CA | Carriers in the population | % |
QQ | Recessive allele frequency (q) | — |
PP | Dominant allele frequency (p) | — |
HD | Homozygous dominant | % |
CR | One carrier in every | — |
Worked example
- Frequency of the recessive phenotype0.04
- Carriers in the population32.0000 %
- Recessive allele frequency (q)0.200000
- Dominant allele frequency (p)0.800000
- Homozygous dominant64.0000 %
- One carrier in every3.13
Limitations
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
- This tool is informational only. It does not diagnose, treat or replace a qualified health professional. Speak to a doctor before making decisions about your health.
Frequently asked questions
What assumptions does this rely on?
Five: a large population, random mating, no migration in or out, no new mutation, and no selection for or against either allele. Real populations break at least one of these, and the deviation is precisely what population geneticists measure. The equilibrium is best used as the null hypothesis to test against, not as a description of reality.