Gene Frequency Calculator (Multiple Alleles)

In genetics, allele frequency measures how common a gene variant is within a population — a foundational calculation in population genetics and evolutionary biology. The Gene Frequency Calculator accepts your population data as genotype counts (AA, Aa, aa), phenotype counts (dominant/recessive), or genotype percentages, then returns the major allele frequency (p) and minor allele frequency (q). Enable the Hardy-Weinberg option to also see expected genotype frequencies (p², 2pq, q²) alongside your total sample size.

Calculation Method *

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Use Hardy-Weinberg to estimate frequencies from phenotype data

Results

Allele p Frequency (Major)

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Allele q Frequency (Minor)

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Total Individuals

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Expected AA (p²)

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Expected Aa (2pq)

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Expected aa (q²)

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Results Table

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Frequently Asked Questions

What is allele frequency?

Allele frequency is the proportion of a particular allele among all alleles at a specific locus in a population. It represents how common or rare an allele is and ranges from 0 (absent) to 1 (fixed in population).

How do you calculate P and Q allele frequency?

For genotype counts: p = (2×AA + Aa) / (2×N) and q = (2×aa + Aa) / (2×N), where N is total individuals. From phenotype data with Hardy-Weinberg: q = √(recessive frequency) and p = 1 - q.

What is the Hardy-Weinberg equation?

The Hardy-Weinberg equation is p² + 2pq + q² = 1, representing expected genotype frequencies in a population. p² is homozygous dominant frequency, 2pq is heterozygous frequency, and q² is homozygous recessive frequency.

How do you find the allele frequency of multiple alleles?

For multiple alleles, count each allele type across all individuals and divide by total alleles. For three alleles (A, B, C): freq(A) = (2×AA + AB + AC) / (2×N). All frequencies must sum to 1.

What do P and Q mean in allele frequency?

P typically represents the frequency of the dominant or major allele, while Q represents the frequency of the recessive or minor allele. Together, p + q = 1 in a two-allele system.

How to calculate minor allele frequency?

Minor allele frequency (MAF) is calculated as the frequency of the less common allele. Count all copies of the minor allele and divide by total alleles (2 × total individuals). MAF is often expressed as a percentage.

When should I assume Hardy-Weinberg equilibrium?

Assume Hardy-Weinberg when the population has random mating, no mutations, no selection, no gene flow, and large population size. It's useful for calculating expected frequencies from phenotype data.