Enter your Parent 1 Genotype and Parent 2 Genotype along with your Dominant and Recessive Alleles, and the Punnett Square Calculator works out the full Genotype Ratio, Phenotype Ratio, and the probability of dominant, recessive, and heterozygous offspring from a single-gene cross.
Genotype Ratio
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Phenotype Ratio
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Dominant Phenotype Probability
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Recessive Phenotype Probability
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Heterozygous Offspring
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A Punnett Square Calculator is a genetic tool that predicts the probability of offspring inheriting specific traits from their parents. It creates a grid showing all possible genetic combinations from a cross between two parents.
Enter the genotypes of both parents using allele letters (e.g., Aa, AA, aa), specify the dominant and recessive alleles, and optionally add phenotype descriptions. The calculator will automatically generate the Punnett square and show ratios.
Genotype ratio shows the proportion of different genetic combinations (like AA:Aa:aa = 1:2:1), while phenotype ratio shows the proportion of observable traits (like Purple:White = 3:1 when A is dominant over a).
A heterozygous genotype has two different alleles (like Aa), while a homozygous genotype has two identical alleles (like AA or aa). Heterozygous individuals carry both dominant and recessive alleles.
A 3:1 phenotype ratio typically results from crossing two heterozygous parents (Aa × Aa). It means 75% of offspring show the dominant trait and 25% show the recessive trait.
This monohybrid calculator is designed for complete dominance patterns. For incomplete dominance or codominance, you would need specialized calculators that account for blended or co-expressed traits.
Punnett squares help predict inheritance patterns, calculate the probability of genetic disorders, plan breeding programs, and understand how traits pass from parents to offspring in sexually reproducing organisms.