Generate monohybrid and dihybrid Punnett squares for any genetic cross. Get genotype ratios, phenotype probabilities, and full inheritance interpretation — including X-linked, incomplete dominance, and codominance.
Choose monohybrid (1 trait) or dihybrid (2 traits), then select how dominance works
Use uppercase for dominant allele, lowercase for recessive (e.g. A / a)
TRAIT A — Gene 1
TRAIT B — Gene 2
Each cell = one possible offspring combination
What you'd actually see in the offspring
Expected counts for different litter / family sizes
Genotype
The genetic makeup (e.g. Aa, BB). Two alleles per gene — one from each parent.
Phenotype
The observable trait (e.g. brown eyes). Determined by genotype + environment.
Dominant Allele
Expressed when at least one copy is present (AA or Aa). Written with uppercase.
Recessive Allele
Only expressed when two copies present (aa). Written with lowercase letter.
Heterozygous (Carrier)
Has one dominant and one recessive allele (Aa). Carries but may not show recessive trait.
Homozygous
Both alleles are the same — either both dominant (AA) or both recessive (aa).
Incomplete Dominance
Heterozygous shows blended phenotype. Red (RR) × White (rr) = Pink (Rr).
Codominance
Both alleles are fully expressed in heterozygote. Blood type AB = both A and B antigens.
Dominant Offspring
Recessive Offspring
Carriers (Heterozygous)
Phenotype Ratio
Genotype Ratio
Cross Classification
| Trait | Dominant | Recessive | Mode | Classic Cross | Recessive Risk |
|---|---|---|---|---|---|
| Eye color (simplified) | Brown | Blue | Complete | Bb × Bb | 25% |
| Attached earlobe | Free lobe | Attached | Complete | Ee × ee | 50% |
| Flower color (snapdragon) | Red | White | Incomplete | Rr × Rr | 25% each |
| Cystic fibrosis | Unaffected | CF affected | Complete | Ff × Ff | 25% |
| Sickle cell anemia | Normal / Trait | Sickle cell | Codominant | Ss × Ss | 25% |
| Color blindness | Normal vision | Color blind | X-Linked | XCXc × XCY | 50% sons |
| Hemophilia A | Normal clotting | Hemophilia | X-Linked | XHXh × XHY | 50% sons |