Punnett Square Calculator
Work out genetic crosses in seconds. Enter each parent's genotype — Aa for a monohybrid cross or AaBb for a dihybrid cross — and see the full Punnett square with genotype and phenotype ratios explained.
Punnett square
Genotype ratio
Phenotype ratio
Uppercase letter = dominant allele, lowercase letter = recessive allele. For a dihybrid cross the phenotype is written per trait, for example A- B- means dominant trait 1 and dominant trait 2.
How to use
- Type each parent's genotype using letters. Use an uppercase letter for the dominant allele and the same lowercase letter for the recessive allele (for example Aa or AaBb).
- For a dihybrid cross, write the two genes one after another (for example AaBb: first pair for trait 1, second pair for trait 2).
- Press Calculate Cross to see the square, genotype ratio and phenotype ratio.
Note
This calculator assumes simple Mendelian inheritance: each gene has two alleles, one dominant and one recessive, and the genes sort independently. Real traits can involve more complex inheritance patterns.