Three-Locus Crosses: Separate Gametes, Genotypes and Phenotypes

Build the cross from gametes

Each added heterozygous locus increases the number of potential gametes. Repeated gametes from homozygous loci are counted with their proper weights. The resulting list is an enumeration of a model, not evidence that every genotype will appear in a particular litter.

Use Trihybrid Cross Calculator - Punnett Square to work through these inputs while keeping the displayed assumptions in view.

Do not infer trait independence from a large table

A larger square still depends on its assumptions. Three entered loci do not establish that the genes are unlinked or that all combinations have equal survival. If those assumptions do not fit, a more specific genetic model is needed rather than a bigger generic square.

This question belongs to the Genetics calculators group within Biology calculators.

Read the calculation on its stated basis

Enumerate each parent’s gametes, combine alleles at each locus, then count genotype and complete-dominance phenotype probabilities.

Assumes independent assortment and complete dominance. Does not model linkage, penetrance, viability effects or an individual clinical genetic risk.

A model is useful only within its assumptions. The result describes the input population or cross; it does not supply missing biological information or replace an appropriate genetic assessment.

Keep related questions separate

Dihybrid Cross Calculator - Punnett Square addresses a related part of the measurement or interpretation task. Check its own method before carrying a value from one tool to the other.

For a related perspective, read The 9:3:3:1 Ratio Depends on Independent Assortment.

For tools in other subjects, return to GreenCalc. Keep the calculator result with its assumptions rather than using a link or a matching unit as evidence that two models are interchangeable.

By GreenCalc · Updated 2026-11-05