Genetics · Education
Punnett Square Calculator
Cross two parents' genotypes and see the full offspring grid, genotype ratios, and phenotype ratios.
Cross Type
🧬 Trait 1
Trait Name
Allele Letter
Dominant =
Recessive =
👪 Parent Genotypes
Parent 1
Trait 1
Parent 2
Trait 1
Assumes simple Mendelian dominance and, for two traits, independent assortment
Trait 1
Dominant 0%
Dominant 0%
Phenotype Ratio
3:1
most to least common
Most Common Phenotype
—
Unique Genotypes
0
Unique Phenotypes
0
Total Offspring Combinations
0
🔳 Punnett Square
📊 Genotype & Phenotype Ratios
| Genotype | Count | Phenotype |
|---|
How this is calculated
Genotype ratio = count of each combination ÷ total | Phenotype = dominant if ≥1 dominant allele present
- Each parent's genotype produces gametes — the possible alleles (or allele combinations, for two genes) it can pass on
- The grid crosses every gamete of Parent 1 against every gamete of Parent 2
- A genotype shows the dominant phenotype if it carries at least one dominant allele for that trait; only fully recessive genotypes show the recessive phenotype
- For two traits, this assumes independent assortment — the genes are on different chromosomes (or far apart), which is the standard classroom simplification
⚠️ This models simple Mendelian dominance for teaching purposes. Real inheritance can involve incomplete dominance, codominance, linked genes, multiple alleles, or polygenic traits — none of which are captured by a basic Punnett square.