What is a trihybrid cross?

A trihybrid cross involves two parents that differ in three gene pairs. Crossing two individuals each heterozygous for three traits (AaBbCc x AaBbCc) produces 64 unique gamete combinations and the classic 27:9:9:9:3:3:3:1 phenotype ratio.

How many offspring genotypes does a trihybrid cross produce?

A trihybrid cross produces up to 27 distinct genotypes across 64 total offspring slots. The Punnett square is an 8x8 grid (8 gametes per parent).

What does the 27:9:9:9:3:3:3:1 ratio mean?

This phenotype ratio applies when both parents are AaBbCc and all three genes show complete dominance. It describes the expected proportion of offspring displaying each combination of dominant and recessive phenotypes.

Can I use homozygous parents?

Yes. Enter genotypes like AABBCC or aabbcc. The tool accepts any combination of homozygous (AA, aa) and heterozygous (Aa) alleles for each of the three gene pairs.

Are these genes assumed to be on different chromosomes?

Yes. The tool assumes independent assortment (Mendel's second law), meaning the three gene pairs are located on different chromosome pairs and do not show linkage.

What notation should I use for alleles?

Use uppercase letters for dominant alleles and lowercase for recessive alleles. Enter each gene pair together, e.g., Aa for heterozygous, AA for homozygous dominant, aa for homozygous recessive.

Punnett Square Trihybrid

Name: Punnett Square Trihybrid
Availability: InStock
Author: Nham Vu

Enter two parent genotypes for three genes and see all 64 offspring genotype combinations with phenotype ratios.

Parent Genotypes

Parent 1

Parent 2

Quick Presets

Legend

All three traits dominant (AAA...)

Two traits dominant

One trait dominant

All three traits recessive

Enter parent genotypes and click Generate to see the Punnett square.

Summary

Enter two parent genotypes for three genes and see all 64 offspring genotype combinations with phenotype ratios.

How it works

Parse each parent genotype into three allele pairs (gene A, gene B, gene C).
Generate all 8 possible gametes for each parent using binary combination logic.
Populate an 8x8 grid by combining each maternal gamete with each paternal gamete.
Determine the phenotype of each offspring by checking for at least one dominant allele per gene.
Count unique genotypes and phenotype classes, then display the ratio summary.

Use cases

Predict offspring ratios in genetics homework and exams.
Verify hand-calculated trihybrid crosses quickly.
Visualize how three independently assorting genes combine.
Teach Mendelian inheritance with an interactive, color-coded grid.
Calculate the probability of a specific phenotype in a cross.
Compare expected ratios for complete dominance in three traits.
Support lab reports that require genotype frequency analysis.
Help students understand the product rule applied across three loci.

Frequently Asked Questions

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Last updated: 2026-05-28 · Reviewed by Nham Vu