🍃 Trihybrid Cross Calculator
Generate Punnett squares, genotype ratios, and phenotype summaries for three-locus crosses.
Provide six alleles covering three genes in order, e.g., AaBbCc or AABBCc.
How to Use This Calculator
Enter parental genotypes
Use six-letter genotypes such as AaBbCc. Maintain consistent gene order between parents.
Generate gamete combinations
Click generate to build the 8×8 matrix of possible offspring combinations under independent assortment.
Review genotype and phenotype ratios
Leverage the calculated counts to predict Mendelian ratios, such as the classic 27:9:9:9:3:3:3:1 phenotypic pattern.
Formula
Gametes per parent = 2n (n = number of heterozygous loci)
Offspring combinations = gametesP1 × gametesP2
Count identical genotypes to derive ratios. For a complete heterozygous cross (AaBbCc × AaBbCc), phenotypes follow 27:9:9:9:3:3:3:1 assuming complete dominance and independent assortment.
Full Description
Trihybrid crosses extend Mendelian analysis to three loci, producing 64 potential genotype combinations in fully heterozygous parents. This calculator automates the combinatorics, revealing both genotype ratios and dominant vs. recessive phenotype patterns.
Use the tool to explore genetic linkage hypotheses, verify expected ratios, or design classroom exercises demonstrating independent assortment and probability theory in classical genetics.
Frequently Asked Questions
How large is the Punnett square for trihybrid crosses?
Up to 8×8 (64 cells) when both parents are heterozygous at all three loci. Homozygous loci reduce the number of distinct gametes.
Does this calculator account for linkage?
No. It assumes independent assortment. Linked genes require recombination frequencies to predict accurate outcomes.
Can I analyze epistasis with this tool?
The calculator provides raw genotype and phenotype counts. You can manually interpret epistatic interactions by grouping phenotypes accordingly.
Why do phenotype labels mention recessive traits?
Each phenotype label highlights genes expressing recessive traits. For example, “A · B · C recessive” indicates dominance at A and B, with recessive expression only for gene C.