Dihybrid Cross Punnett Square Calculator

A Punnett square is a grid used in genetics to predict the traits offspring might inherit from two parents — the Dihybrid Cross Punnett Square Calculator extends this to two traits at once, across all 16 possible offspring combinations. Enter the alleles for Parent 1 and Parent 2 across both traits, add optional phenotype labels (like Brown Eyes or Dark Hair), and get a full 4×4 Punnett square with the probability of both dominant traits, both recessive traits, heterozygous outcomes, and the total number of distinct genotypes.

Enter dominant allele (usually uppercase)

Enter recessive allele (usually lowercase)

Enter dominant allele for second trait

Enter recessive allele for second trait

Enter dominant allele (usually uppercase)

Enter recessive allele (usually lowercase)

Enter dominant allele for second trait

Enter recessive allele for second trait

Label for dominant trait 1 phenotype

Label for recessive trait 1 phenotype

Label for dominant trait 2 phenotype

Label for recessive trait 2 phenotype

Display detailed ratio analysis

Show probability as percentages

Results

Probability of Both Dominant Traits

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Probability of Both Recessive Traits

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Probability of Heterozygous for Both

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Total Possible Genotypes

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Results Table

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Frequently Asked Questions

How do you perform a dihybrid cross?

A dihybrid cross involves crossing two organisms that are heterozygous for two different traits. Each parent contributes four possible gametes, creating a 4×4 Punnett square with 16 possible offspring combinations.

What is the typical phenotype ratio in a dihybrid cross?

The classic dihybrid cross between two heterozygous parents (AaBb × AaBb) produces a 9:3:3:1 phenotype ratio. This means 9 dominant-dominant, 3 dominant-recessive, 3 recessive-dominant, and 1 recessive-recessive.

How do you calculate probability in a dihybrid cross?

Probability is calculated by dividing the number of desired outcomes by the total possible outcomes (16). For example, the probability of both recessive traits is 1/16 = 6.25%.

What are gametes in a dihybrid cross?

Gametes are the reproductive cells that carry one allele for each trait. In a dihybrid cross, each parent can produce four different types of gametes (e.g., AB, Ab, aB, ab).

What is the difference between genotype and phenotype ratios?

Genotype ratios show the genetic makeup (like AaBb), while phenotype ratios show the observable traits. A dihybrid cross typically has 9 different genotypes but only 4 phenotypes.

What is the probability of getting both homozygous recessive traits?

In a typical dihybrid cross (AaBb × AaBb), the probability of offspring with both homozygous recessive traits (aabb) is 1/16 or 6.25%.

How many squares are in a dihybrid Punnett square?

A dihybrid Punnett square has 16 squares (4×4 grid) because each parent can produce 4 different types of gametes, resulting in 16 possible combinations.