1
0.345
0.655
0.873333
2.8986
0
1
0.345
0.655
0.873333
2.8986
0
The Heterozygosity Calculator computes expected heterozygosity (gene diversity) from allele frequencies. Expected heterozygosity is a fundamental measure of genetic variation within a population. It represents the probability that two randomly chosen alleles at a locus are different, and is widely used in population genetics, conservation biology, and forensic genetics.
Enter the frequencies of up to three alleles (set unused alleles to 0) to calculate expected heterozygosity using Nei's formula.
Expected heterozygosity (H) is calculated using Nei's gene diversity formula:
H = 1 − Σ(pᵢ²)
Where pᵢ is the frequency of the i-th allele. For a two-allele system, this simplifies to H = 2pq = 1 − p² − q². The homozygosity is Σ(pᵢ²), and heterozygosity is its complement. Allele frequencies should sum to 1.0 for accurate results.
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With three alleles at frequencies 0.40, 0.35, and 0.25, expected heterozygosity is 0.665, meaning there is a 66.5% chance that two randomly sampled alleles are different.
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For a two-allele system with p=0.7 and q=0.3, expected heterozygosity is 0.42 (equivalent to 2pq = 2×0.7×0.3 = 0.42).
Expected heterozygosity (H or He) measures the genetic diversity at a locus. Higher H means more diversity. H = 0 means the locus is monomorphic (only one allele). The maximum H depends on the number of alleles: for k equally frequent alleles, H_max = 1 − 1/k. For 2 alleles, maximum H is 0.5; for 10 alleles, maximum H is 0.9.
Allele frequencies at a single locus must sum to 1.0. If your values do not sum to 1, check for rounding errors or missing alleles. The calculator will show the sum so you can verify. Results are only meaningful when the sum equals 1.0 (within rounding tolerance).
Expected heterozygosity (He) is calculated from allele frequencies assuming Hardy-Weinberg equilibrium. Observed heterozygosity (Ho) is the actual proportion of heterozygous individuals in the sample. Comparing Ho and He tests for Hardy-Weinberg equilibrium: if Ho < He, there may be inbreeding or population structure (Wahlund effect).
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