Math July 13, 2026 · 8 Min Read

Trihybrid Cross Calculator – Guide & Formulas

Generate trihybrid cross Punnett squares for three simultaneous traits. Calculate genotype and phenotype ratios for AaBbCc x AaBbCc crosses with full 64-box grid.

Generate complete trihybrid cross Punnett squares for three independent traits. Calculate phenotype and genotype ratios for AaBbCc crosses with 64 offspring combinations.

Key Takeaway

Use the free Trihybrid Cross Calculator to generate trihybrid cross punnett squares for three simultaneous traits. calculate genotype and phenotype ratios for aabbcc x aabbcc crosses with full 64-box grid. Get instant results with step-by-step explanations.

How to Use the Trihybrid Cross Calculator

  1. Enter the genotype for Parent 1 (e.g., AaBbCc for triple heterozygote).
  2. Enter the genotype for Parent 2 (e.g., AaBbCc for triple heterozygote).
  3. Use three different letters to represent three independent genes.
  4. Review the complete 64-box Punnett square grid.
  5. Analyze the phenotypic ratio, genotypic ratio, and probability for each combination.

The Formula

For a trihybrid cross AaBbCc x AaBbCc: phenotypic ratio = 27:9:9:9:9:3:3:3:1 (all dominant to all recessive). Total combinations = 4^3 = 64. Each gene follows Mendelian 3:1 ratio independently. Combined probability = P(A phenotype) x P(B phenotype) x P(C phenotype).

Variable Definitions

  • 27:9:9:9:9:3:3:3:1: Phenotypic ratio for three independent dominant-recessive traits
  • 64: Total number of unique gamete combinations (4 x 4 x 4)
  • AaBbCc: Triple heterozygous genotype for three independent genes
  • 3/4: Probability of dominant phenotype for each gene in Aa x Aa cross
  • 1/4: Probability of recessive phenotype for each gene in Aa x Aa cross

Trihybrid Cross: AaBbCc x AaBbCc

Calculate phenotypic ratios for a cross between two triple heterozygotes for seed color (A/a), seed shape (B/b), and plant height (C/c).

  1. Step 1: Each parent produces 8 possible gametes: ABC, ABc, AbC, Abc, aBC, aBc, abC, abc (each at 1/8 frequency).
  2. Step 2: Create 8x8 Punnett square (64 total squares) by combining all gamete pairs.
  3. Step 3: For phenotype: count dominant alleles at each locus. A_ = dominant phenotype, aa = recessive, etc.
  4. Step 4: Phenotypic ratio: 27 A_B_C_ : 9 A_B_cc : 9 A_bbC_ : 9 aaB_C_ : 3 A_bbcc : 3 aabbC_ : 3 aaB_cc : 1 aabbcc.
  5. Step 5: Verify: 27+9+9+9+9+3+3+3+1 = 64 total combinations. Each phenotype class probability = count/64.

Frequently Asked Questions

What is a trihybrid cross?

A trihybrid cross involves two parents that are heterozygous for three independent genes (e.g., AaBbCc x AaBbCc). It produces 64 possible offspring combinations in the Punnett square and yields the classic 27:9:9:9:9:3:3:3:1 phenotypic ratio.

How many gametes does each parent produce in a trihybrid cross?

Each triple-heterozygous parent (AaBbCc) produces 2^3 = 8 different gametes: ABC, ABc, AbC, Abc, aBC, aBc, abC, abc, each at equal 1/8 frequency assuming independent assortment.

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

It means: 27/64 show all three dominant traits, 9/64 show two dominant and one recessive (three such classes), 3/64 show one dominant and two recessive (three classes), and 1/64 shows all three recessive traits.

Does this calculator handle linked genes?

This calculator assumes independent assortment (genes on different chromosomes or far apart on the same chromosome). Linked genes violate independent assortment and produce modified ratios with excess parental-type offspring.

How do I determine genotypes from the Punnett square?

Each cell in the 64-box grid contains a specific genotype (e.g., AaBbCc, AABbcc, etc.). Count identical genotypes to get the genotypic ratio. Many different genotypes can produce the same phenotype.

Can I use different genotypes for each parent?

Yes. While the classic trihybrid uses AaBbCc x AaBbCc, you can input any combination (e.g., AaBbCc x aabbcc for a test cross). The calculator will generate the appropriate 8x8 grid and ratios.