Punnett Square Calculator
Enter the genotype of each parent for a single gene to see the predicted genotype and phenotype ratios of their offspring, just like a classic Punnett square.
What this calculator does
A Punnett square is a simple grid used in genetics to predict the possible genotype and phenotype combinations that can result from crossing two parents for a single gene with two alleles (a dominant allele, shown as an uppercase letter, and a recessive allele, shown as lowercase). Pick the genotype of each parent and this tool works out every possible pairing of their alleles, just as you would by hand on a 2×2 grid.
How the math works
Each parent contributes one allele per offspring. The calculator lists all possible allele combinations from the two parents, tallies how many result in each genotype (AA, Aa, or aa), and converts those counts into percentages. Because A is dominant, any offspring with at least one A allele shows the dominant phenotype; only aa offspring show the recessive phenotype.
Good to know
This model assumes simple Mendelian dominance for a single gene and does not account for traits controlled by multiple genes, incomplete dominance, codominance, or linked genes. It is intended for general educational use in understanding basic inheritance patterns, not as a substitute for a genetics course or professional genetic counseling.