Punnett Square Calculator
Calculate the probability of offspring genotypes and phenotypes from two parent genotypes using a Punnett square.
Published by:
isCalculator Editorial Team
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How to Use the Punnett Square Calculator
This tool calculates genotype and phenotype probabilities for genetic crosses. Follow these steps:
- Enter Parent Genotypes – Type the genotype for Parent 1 and Parent 2 (e.g.,
AaBb). Use only letters; the length must be even (e.g., 2, 4, 6 letters). - Set Dominant and Recessive Alleles – Enter a single letter for the dominant allele (e.g.,
A) and a single letter for the recessive allele (e.g.,a). These must match the letters used in the genotypes. - Click "Calculate" – The calculator validates inputs and displays:
- Punnett Square – A table showing all possible offspring genotypes.
- Genotype Probabilities – Percentage chance of each genotype.
- Phenotype Probabilities – Percentage chance of dominant/recessive traits.
- Check for Errors – If inputs are invalid (e.g., wrong letters or odd length), error messages appear below the fields.
Note: Use uppercase for dominant and lowercase for recessive alleles (e.g., A and a). The calculator works for monohybrid, dihybrid, or multi-trait crosses.
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Frequently Asked Questions
A Punnett square is a diagram used in genetics to predict the probability of offspring genotypes from a cross between two parents.
Enter genotypes as a string of letters, e.g., 'AaBb' for a dihybrid cross. Each pair of letters represents one gene. Use the same letters for dominant and recessive alleles.
The calculator supports any number of genes as long as the genotype length is even. Each pair of letters corresponds to one gene.