Allele Frequency Calculator

Population genetics relies heavily on the Hardy-Weinberg principle, which models genetic equilibrium in a non-evolving population. The primary equations used are p + q = 1, representing the total frequency of alleles in a gene pool, and p^2 + 2pq + q^2 = 1, representing the genotype frequencies. Here, 'p' is the frequency of the dominant allele, 'q' is the frequency of the recessive allele, 'p^2' is the homozygous dominant genotype frequency, '2pq' is the heterozygous genotype frequency, and 'q^2' is the homozygous recessive genotype frequency. When you input a known value like the disease incidence (q^2), the calculator takes the square root to find q, and subsequently derives p by subtracting q from 1.

Imagine studying a rare autosomal recessive genetic disorder that affects 1% of a given population. This means the frequency of homozygous recessive individuals (q^2) is 1 percent, or 0.01. First, we find the recessive allele frequency (q) by taking the square root of q^2: the square root of 0.01 equals 0.10, meaning q = 0.10. Next, we determine the dominant allele frequency (p) using the equation p = 1 - q, which gives us p = 1 - 0.10 = 0.90. Finally, we calculate the carrier frequency (heterozygotes, represented by 2pq) by multiplying 2 * 0.90 * 0.10, resulting in 0.18, or 18 percent of the population carrying the trait.

Always ensure your input data reflects a population in Hardy-Weinberg equilibrium before drawing evolutionary conclusions, as migration, non-random mating, or selection can skew real-world results. When working with percentages, remember to convert them into decimals (e.g., 5% becomes 0.05) before running algebraic operations. Double-check whether your input represents a phenotype (like homozygous recessive individuals) or a direct allele count to select the correct calculation path.