Biology
Allele Frequency Calculator
Estimate allele frequencies p and q in a population from observed genotype counts (AA, Aa, aa).
Your inputs
Change any value to update the result instantly.
Frequency of allele A (p)
0.8
Frequency of allele a (q)
0.2
Sample size (N)
500 individuals
Alleles counted
1,000
p + q check
1
Frequencies describe the gene pool at this one locus. The counting method needs distinguishable genotypes; if heterozygotes look identical to dominant homozygotes, use the Hardy-Weinberg calculator instead.
What this calculator does
Estimates allele frequencies p and q from observed diploid genotype counts at one two-allele locus.
What your result means
p and q are the proportions of each allele in the sampled gene pool; they must sum to 1.
Formula and working
p = (2 × AA + Aa) ÷ 2N; q = (2 × aa + Aa) ÷ 2N; p + q = 1
- 1
Collect the inputs
Individuals with genotype AA = 320; Individuals with genotype Aa = 160; Individuals with genotype aa = 20
- 2
Apply the formula
p = (2 × AA + Aa) ÷ 2N; q = (2 × aa + Aa) ÷ 2N; p + q = 1
- 3
Result
Frequency of allele A (p) = 0.8
Frequently asked questions
Symbols and assumptions
- p
- Frequency of allele A
- q
- Frequency of allele a
- N
- Number of individuals sampled
- • A single autosomal locus with two alleles.
- • All three genotypes (AA, Aa, aa) are distinguishable.
Sources and review
Reviewed 2026-09-22 · Next review 2027-09-22
- • Multi-allelic loci and X-linked loci need extended methods; phenotype-only counts require Hardy-Weinberg assumptions.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
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