Understand the relationship
The reasoning behind the result
Genotypes count individuals; alleles count copies
p = (2nAA+nAa)/(2N); q = (2naa+nAa)/(2N)
Each AA individual contributes two A copies, each Aa contributes one of each, and each aa contributes two a copies. Dividing by 2N gives allele frequencies for the typed diploid sample. Dividing each genotype count by N gives observed genotype frequencies.
A sample consisting entirely of heterozygotes has p=q=0.5 and an observed Aa frequency of 1. The Hardy–Weinberg expectation at those allele frequencies would be 0.5 Aa, but replacing the observed value with that expectation would erase the data.
Pooling uses counts before division
A ten-copy record and a hundred-copy record do not get equal weight in a pooled frequency. Add the allele counts across compatible records, then divide by their combined total. The table preserves each record so differences remain visible.
The pooled result is a descriptive tally. Mixed populations, repeated individuals, inconsistent allele definitions or incompatible sampling can make a pooled biological interpretation inappropriate.
Direct allele counts cannot reconstruct genotypes
Knowing A and a copy counts determines p and q. It does not reveal how the copies are paired into individuals: the same counts can come from different numbers of homozygotes and heterozygotes. The direct-count mode therefore omits genotype proportions and an inferred number of individuals.
These tools support two specified alleles. Missing calls, genotype uncertainty, sequencing errors, mixed ploidy and additional alleles require an appropriate analysis method before entering counts.
Follow the numbers
Why two record percentages cannot simply be averaged
- Sample A has 40 AA, 40 Aa and 20 aa: 120 A copies and 80 a copies.
- Sample B has 0 AA, 10 Aa and 10 aa: 10 A copies and 30 a copies.
- The pooled totals are 130 A copies and 110 a copies, across 240 copies.
- The pooled a frequency is 110/240=45.833333…%. The unweighted mean of 40% and 75% would incorrectly give 57.5%.
The count-weighted result preserves the larger first sample's contribution without concealing the record-level difference.
Quick guide
How to use this calculator
- Choose observed diploid genotype counts or direct allele-copy counts.
- Keep the same A/a allele definitions across records and exclude untyped observations from these denominators.
- Read record-level frequencies before the pooled summary. Pooling is count-weighted and does not establish that records represent one biological population.
Calculation method
Calculation and interpretation
Keep measured genotype proportions and allele-copy proportions on their correct denominators.
A copies=2nAA+nAa; a copies=2naa+nAa; p=A/(A+a), q=a/(A+a). Observed genotype frequency=nGenotype/Ntyped.
Worked example
Why two record percentages cannot simply be averaged
The count-weighted result preserves the larger first sample's contribution without concealing the record-level difference.
A copies=2nAA+nAa; a copies=2naa+nAa; p=A/(A+a), q=a/(A+a). Observed genotype frequency=nGenotype/Ntyped.
Supported inputs
Precision and limits
Observed arithmetic only
No Hardy–Weinberg equilibrium, population representativeness, inheritance pattern, ancestry, disease risk or clinical interpretation is inferred.
Compatible typed counts
Use up to 100 uniquely labelled records and nonnegative whole counts, with at least one observed copy per record. Genotype mode requires diploid two-allele observations. Direct copy mode does not infer ploidy or genotype pairing.
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