Trihybrid Cross Calculator – Punnett Square

Related Calculators

Genotype: The allele letters an organism has, such as AaBbCc.

Phenotype: The visible trait pattern produced by a genotype, such as dominant showing or recessive showing for each trait.

Gamete: A sex cell that carries one allele from each gene pair. Gametes from each parent combine to make offspring.

Dominant showing: A trait that appears when at least one uppercase allele is present, written in this calculator as A- or B- or C-.

Recessive showing: A trait that appears only when both alleles are lowercase, such as aa, bb, or cc.

Target phenotype pattern: An optional pattern you want to test, written with 3 parts like A- bb C-.

Exact genotype to check: An optional full offspring genotype, such as AaBbCc, used to find the chance of one exact allele combination.

Total offspring combinations: The number of cells in the Punnett square based on the unique gametes from both parents.

Mistake: Entering fewer or more than 3 gene pairs in Parent 1 genotype or Parent 2 genotype , such as AaBb or AaBbCcDd.
Fix: Use exactly 6 letters total, grouped as 3 pairs, like Aa Bb Cc.

Mistake: Using a different gene order between Parent 1 genotype and Parent 2 genotype , such as AaBbCc versus BbAaCc.
Fix: Keep the same gene family order in both inputs: A pair first, B pair second, C pair third.

Mistake: Typing malformed pairs in Parent 1 genotype , Parent 2 genotype , or Exact genotype to check , such as AAA, A, or A1.
Fix: Each gene pair must use letters only and contain exactly 2 alleles from the same family, such as AA, Aa, or aa.

Mistake: Writing the Target phenotype pattern in an unsupported format, such as Aa Bb Cc.
Fix: Use A- for a dominant-showing trait or aa for a recessive-showing trait, and match all 3 genes, like A- bb C-.

Mistake: Reading Offspring genotype summary and Offspring phenotype summary as if they mean the same thing.
Fix: Use Offspring genotype summary for allele combinations and Offspring phenotype summary for visible traits.

Mistake: Expecting Per-trait probability breakdown to work for linked genes or non-Mendelian inheritance.
Fix: Use the breakdown only when the 3 traits assort independently and follow simple dominant-recessive inheritance.

• This calculator assumes complete dominance for each gene pair, so one uppercase allele is treated as dominant showing.
• This calculator assumes independent assortment when it combines per-trait probabilities, so linked genes can give different real results.
• It is built for exactly 3 gene pairs in matching order and does not handle monohybrid, dihybrid, or 4-trait crosses.
• Phenotype labels are simplified to dominant-showing versus recessive-showing outcomes unless you enter custom trait names and labels.
• The full square and summaries show theoretical probabilities, not guaranteed results for a small real offspring sample.
• It does not model codominance, incomplete dominance, multiple alleles, sex linkage, mutation, or environmental effects on traits.

How the calculator works

The calculator reads Parent 1 genotype and Parent 2 genotype as 3 gene pairs in order. It checks that both parents use the same gene families in the same order, then it generates every possible gamete each parent can make. Next, it combines every gamete from Parent 1 with every gamete from Parent 2 to build all possible offspring outcomes, just like a Punnett square [1].

Core formulas

gamete_count = 2^h

Here, h is the number of heterozygous pairs in one parent. Each heterozygous pair doubles the number of unique gametes.

square_cells = gametes_parent1 * gametes_parent2

This gives the Total offspring combinations. For AaBbCc x AaBbCc, each parent makes 8 gametes, so the full square has 64 combinations.

P(combined phenotype) = P(trait 1 outcome) * P(trait 2 outcome) * P(trait 3 outcome)

This product rule is used for the Per-trait probability breakdown and for Target phenotype chance when a valid target pattern is entered [2].

percent = probability * 100

How genotype and phenotype summaries are built

For each offspring combination, the calculator standardizes each gene pair so the uppercase allele is shown first when present, such as Aa instead of aA. Matching offspring genotypes are grouped together for the Offspring genotype summary. Then those genotypes are translated into phenotype classes by checking whether each trait shows a dominant form, written like A-, or a recessive form, written like aa.

Worked mini-example

Suppose the cross is AaBbCc x AaBbCc and the target phenotype is A- B- C-. For one trait, Aa x Aa gives a 3/4 chance of dominant showing. Because the 3 traits are treated independently here, the combined chance is:

P(A- B- C-) = (3/4) * (3/4) * (3/4) = 27/64 = 42.1875%

If the exact target genotype is AaBbCc, then each trait has a 1/2 chance of being heterozygous in an Aa x Aa cross, so:

P(AaBbCc) = (1/2) * (1/2) * (1/2) = 1/8 = 12.5%

How to interpret the results

Parent 1 gametes and Parent 2 gametes show how each parent's alleles split into possible sex cells. Offspring genotype summary tells you the allele combinations you can get. Offspring phenotype summary tells you what traits are expected to show. If you entered a target pattern, the probability cards give the chance for that one requested outcome.

Assumptions behind the math

The calculator is most accurate for basic Mendelian genetics problems with 3 independently assorting genes and simple dominant-recessive inheritance. Real organisms can differ when genes are linked or when inheritance is not complete dominance, so classroom answers and real biological systems do not always match exactly.