horse color calculator

How this horse color calculator works

This horse color calculator uses Mendelian inheritance probabilities to estimate likely coat colors in a foal. You enter genotype data for the stallion and mare, and the tool computes all possible offspring combinations across the selected loci. It then converts those genotype combinations into likely phenotypes such as chestnut, bay, black, palomino, buckskin, cremello, perlino, smoky black, smoky cream, and gray overlays.

The output is probabilistic, not absolute. Real-world horse color outcomes can be influenced by additional genes and modifiers that are not included in this simplified model. Still, this is an effective breeding-planning reference for many common coat color predictions.

Genetics primer: the four loci in this model

1) Extension locus (E/e)

The Extension locus controls whether black pigment can be produced in the coat:

• EE or Ee: black pigment is possible.
• ee: no black pigment, resulting in a red/chestnut base.

2) Agouti locus (A/a)

Agouti controls distribution of black pigment, but only when a horse has at least one E allele:

• A_ (AA or Aa): restricts black to points, producing bay-based colors.
• aa: no restriction, producing black-based colors.
• When a horse is ee, Agouti has no visible effect.

3) Cream dilution (N/Cr)

The Cream gene dilutes coat color in a dose-dependent way:

• NN: no cream dilution.
• NCr: single cream dilution (e.g., palomino, buckskin, smoky black).
• CrCr: double cream dilution (e.g., cremello, perlino, smoky cream).

4) Gray locus (G/g)

Gray is dominant and progressive over time:

• G_ (GG or Gg): horse will gray out as it ages.
• gg: horse does not gray.

Foals with gray genes are born a base color (such as bay or chestnut) and gradually lose pigment over the years.

How to use this calculator effectively

1. Enter the sire genotype for Extension, Agouti, Cream, and Gray.
2. Enter the dam genotype for the same loci.
3. Click Calculate Foal Color Odds.
4. Review the sorted probability table and gene-by-gene inheritance breakdown.

For better accuracy, use DNA-verified genotypes whenever possible. Visual color alone can sometimes hide genotype details (especially with gray horses and subtle dilutions).

Important limitations and breeding notes

This calculator is educational and practical, but not exhaustive. Horse coat color genetics can include additional loci such as Dun, Champagne, Silver, Roan, Tobiano, Frame Overo, Sabino, and more. Those genes can dramatically change visible phenotype and patterning.

• Use this as a planning aid, not a guarantee.
• Always confirm with reputable equine DNA testing where decisions matter.
• Prioritize health, conformation, and temperament over color alone.

Example interpretation

If one parent is Ee and the other is ee, you can expect around a 50/50 split between offspring that can produce black pigment (Ee) and those that cannot (ee). If both parents also carry one cream allele (NCr), your foal has chances for single-cream colors and a smaller chance of double-cream outcomes.

When one parent is gray heterozygous (Gg) and the other is non-gray (gg), approximately half of foals are expected to gray out over time.

Final thoughts

Whether you are planning a cross, teaching horse color genetics, or simply curious about possibilities, a horse color calculator can make complex inheritance easier to understand. Pair this tool with pedigree analysis and DNA testing for the best decision-making.