Punnett Square Calculator

Build monohybrid, dihybrid, and trihybrid Punnett squares plus ABO blood type and X-linked crosses, with reduced genotypic and phenotypic ratios, gametes, and every genetic convention named.

Cross type

Uppercase = dominant allele, lowercase = recessive.

Both parents use the same trait letters.

Phenotype rows and the phenotypic ratio.

Optional phenotype labels

Punnett square

Enter a cross

Monohybrid, dihybrid, trihybrid, ABO blood type, and X-linked crosses.

Genotype summary
OutcomeCountFractionPercent
Phenotype summary
OutcomeCountFractionPercent
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    parent gametes are combined in a Cartesian grid How?

    How this is calculated

    Each parent's genotype is read exactly as entered, so the probabilities follow from what you type and the heterozygous case is never inferred. The calculator lists every gamete each parent can make, combines each parent 1 gamete with each parent 2 gamete, counts the resulting genotypes, and reduces the counts to the genotypic and phenotypic ratio.

    The case-dominance modes (monohybrid, dihybrid, trihybrid) read uppercase as dominant. ABO blood type uses a three-allele codominance model where I^A and I^B are codominant and both dominant over i. X-linked crosses treat the Y as carrying no allele, so males are hemizygous and phenotype is reported per sex.

    Formula: parent gametes are combined in a Cartesian grid

    Sources

    1. OpenStax Biology 2e, Characteristics and Traits. OpenStax. Retrieved .
    2. Biology LibreTexts, Multiple Alleles. LibreTexts. Retrieved .
    3. OpenStax Biology 2e, Laws of Inheritance. OpenStax. Retrieved .

    Method last reviewed