Punnett square calculator
Enter two parent genotypes to see the square and the offspring ratios.
Write each gene as two letters, uppercase for dominant and lowercase for recessive. Use one gene (Aa) or two (AaBb). Results assume complete dominance and independent assortment.
Reading the square
Each parent passes on one allele per gene. The calculator lists every possible gamete, pairs them in a grid, and counts the resulting genotypes. With two genes it assumes they sort independently, which gives the classic 4 × 4 square.
Phenotypes assume complete dominance: an uppercase letter shows the dominant trait, and two lowercase letters show the recessive one. Linked genes, incomplete dominance, and codominance follow different rules.