Animal Genetics Color Calculator
This simplified calculator models two common coat-color loci: B/b (black vs brown pigment) and D/d (full color vs dilute). Choose each parent's genotype to estimate offspring color probabilities.
Parent A
Parent B
Phenotype Probabilities
Genotype Probabilities
| Genotype (B locus + D locus) | Probability |
|---|
Note: This tool is educational and assumes independent assortment, complete dominance, and no epistasis beyond the two modeled loci.
What this calculator does
The animal genetics color calculator helps you estimate how coat color traits may appear in offspring using a two-locus Mendelian model. It is useful for breeders, students, and hobby geneticists who want a fast, visual way to understand inheritance patterns.
Instead of manually building Punnett squares for each locus and then combining probabilities, this calculator automates the math and returns:
- Predicted phenotype percentages (visible color outcomes)
- Predicted genotype percentages (underlying allele combinations)
- A quick summary of the most likely offspring color category
Genetic model used in this tool
B locus (black vs brown pigment)
At the B locus, the dominant allele B produces black eumelanin pigment, while bb produces brown/chocolate pigment. In this simplified model:
- B_ = black-base pigment
- bb = brown/chocolate-base pigment
D locus (dilution)
The D locus controls pigment intensity. The dominant allele D keeps full intensity, while dd dilutes color.
- D_ = full color intensity
- dd = dilute expression
Combined phenotype outcomes
- B_ D_ → Black
- bb D_ → Brown / Chocolate
- B_ dd → Blue / Gray (dilute black)
- bb dd → Lilac / Isabella (dilute brown)
How to use it
- Select Parent A genotypes for B and D loci.
- Select Parent B genotypes for B and D loci.
- Click Calculate Offspring Colors.
- Review phenotype and genotype probabilities.
For a classic test cross example, try Bb Dd × Bb Dd to see a broad range of outcomes.
Why this matters for breeding plans
Color outcomes can influence breeding goals, registration preferences, and market expectations in some species and lines. A calculator like this supports better planning by showing risk and likelihood rather than guessing from a single litter outcome.
- Identify whether dilute offspring are possible (dd appears only if both parents pass d)
- Estimate probability of recessive brown/chocolate (bb)
- See hidden carrier scenarios (for example, Bb or Dd)
Important limitations
Real-world coat color genetics can be far more complex than two loci. Many species involve additional genes, modifiers, epistasis, incomplete dominance, and pattern genes that alter final appearance.
This calculator should be treated as a foundational teaching tool, not a full breeding certification system.
Final thoughts
If you're learning genetics, this is a practical way to connect genotype math with visible phenotype outcomes. Start simple with two loci, then expand your understanding to species-specific genes, DNA testing, and pedigrees for more accurate predictions.