Punnett Square Calculator

A Punnett square is a genetics chart used to predict the possible genotypes and phenotypes of offspring from a genetic cross. It shows how alleles from each parent can combine during reproduction.

How to Use the Punnett Square Calculator

1. Select the number of traits in the cross.
2. Enter the genotype of Parent 1 and Parent 2.
3. Add trait labels if you want clearer phenotype results.
4. Click Calculate to see the Punnett square, genotype ratio, phenotype ratio, and explanation.

Monohybrid Cross Calculator

A monohybrid cross follows one trait at a time. Examples include Aa × Aa, Aa × aa, and AA × aa. This is usually the first type of Punnett square students learn.

Dihybrid Cross Calculator

A dihybrid cross follows two traits at the same time, such as AaBb × AaBb. A classic 9:3:3:1 phenotype ratio appears only when both traits show complete dominance and assort independently.

Genotype vs Phenotype

A genotype is the allele combination an organism carries. A phenotype is the trait that appears or can be observed. For example, Aa is a genotype, while the visible dominant trait is the phenotype.

Dominant and Recessive Inheritance

A dominant allele can affect the phenotype when one copy is present. A recessive allele usually affects the phenotype only when two recessive copies are present. Dominant does not mean common, and recessive does not mean weak.

When Punnett Squares Are Most Useful

Punnett squares work best for simple Mendelian inheritance patterns. They are especially useful for learning about alleles, carriers, genotype ratios, phenotype ratios, and how traits can appear or remain hidden across generations.

Limits of Punnett Squares

Real inheritance can be more complex than a basic Punnett square. Some traits involve incomplete dominance, codominance, multiple alleles, multiple genes, gene linkage, sex linkage, epistasis, environmental effects, or random developmental variation.

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