Trihybrid Cross Calculator

Predict the genotypic and phenotypic ratios of offspring for crosses involving three independent genes.

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Parental Genotypes

Select genotypes for Mother and Father across Gene 1 (A/a), Gene 2 (B/b), and Gene 3 (C/c).

Parent 1 (Mother)

Gene 1 (A)

Gene 2 (B)

Gene 3 (C)

Parent 2 (Father)

Gene 1 (A)

Gene 2 (B)

Gene 3 (C)

Genotypic Breakdown (All 27 Combinations)

Trihybrid Ratios

Phenotypic Probabilities (Simple Dominance)

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Triple Heterozygote Cross

When crossing two triple heterozygotes (AaBbCc × AaBbCc), the phenotypic ratio for the three traits is 27:9:9:9:3:3:3:1.

Trihybrid Cross 27:9:9:9:3:3:3:1 Phenotype Reference Table

Phenotype Category	Genotype Format	Mendelian Ftion	Probability (%)
Triple Dominant	A_B_C_	27 / 64	42.19%
A & B Dominant, C Recessive	A_B_cc	9 / 64	14.06%
A & C Dominant, B Recessive	A_bbC_	9 / 64	14.06%
B & C Dominant, A Recessive	aaB_C_	9 / 64	14.06%
A Dominant, B & C Recessive	A_bbcc	3 / 64	4.69%
B Dominant, A & C Recessive	aaB_cc	3 / 64	4.69%
C Dominant, A & B Recessive	aabbC_	3 / 64	4.69%
Triple Recessive	aabbcc	1 / 64	1.56%

Calculation Methodology & Biological Principles

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Product Rule of Probability

Instead of making an 8×8 grid (64 cells), we calculate the probability of each gene pair independently and multiply them together:

P(AaBbCc) = P(Aa) × P(Bb) × P(Cc)

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The 8 Phenotypic Classes

Assuming complete dominance, three genes yield 2³ = 8 unique phenotype categories ranging from triple dominant (27/64) to triple recessive (1/64).

Frequently Asked Questions

What is a Trihybrid Cross? ▼

A trihybrid cross is a genetic breeding experiment between two individuals that analyzes the inheritance patterns of three independent, unlinked gene traits simultaneously.

Why use probability product rules instead of an 8x8 Punnett square grid? ▼

An 8x8 Punnett square produces 64 grid boxes, which is cumbersome and prone to human error. Applying the probability product rule across each gene independently yields exact genotype and phenotype probabilities instantly.

What is the classic phenotypic ratio of a trihybrid cross? ▼

Crossing two triple-heterozygous parents (AaBbCc × AaBbCc) yields a 27:9:9:9:3:3:3:1 phenotypic ratio across 8 distinct phenotype categories.