Equine Color Calculator — Predict Foal Coat Colors Instantly

Enter sire and dam coat colors to see possible foal colors with probability percentages. Free equine color genetics predictor using Extension & Agouti genes, step‑by‑step Punnett logic, and breeding guidance.

Mendelian Genetics Instant Breakdown Privacy First

Equine Color Calculator

Select the sire and dam base colors to see potential foal coat colors and their probabilities.

Choose both parent colors and click Estimate Foal Colors to see the probability breakdown.

Horse Coat Color Genetics Explained

The equine coat color calculator uses Mendelian inheritance of two key genes: Extension (E/e) and Agouti (A/a). These genes interact to produce the three base coat colors in horses.

Phenotype = f(Extension, Agouti) → Chestnut (ee), Bay (E_ A_), Black (E_ aa)

Gene Functions

  • Extension (MC1R): Dominant E allows black pigment; recessive e restricts to red pigment only.
  • Agouti (ASIP): Dominant A restricts black to points (mane, tail, legs); recessive a allows uniform black.
  • Combinations: ee = Chestnut regardless of Agouti; E_ A_ = Bay; E_ aa = Black.

The calculator maps visible colors to possible genotypes, then builds Punnett squares to compute foal probabilities.

How to Predict a Foal's Coat Color

  1. Identify parent colors — Determine the base coat of the stallion and mare: Black, Bay, or Chestnut.
  2. Map to genotypes — Each color may hide recessive alleles (e.g., a Black horse could be EEaa or Eeaa). The calculator considers all possible genotype combinations.
  3. Build Punnett squares — For each gene, cross the possible allele contributions from both parents.
  4. Combine probabilities — Multiply independent gene probabilities to get overall color chances.
  5. View the breakdown — The calculator displays percentages for Chestnut, Bay, and Black foals.

Equine Color Calculator Examples

Example 1: Bay × Chestnut

Sire: Bay (genotype possibilities: EEAA, EEAa, EeAA, EeAa). Dam: Chestnut (ee).

Chestnut: 25% · Bay: 56.25% · Black: 18.75%

Example 2: Black × Black

Both parents Black (possible genotypes: EEaa, Eeaa).

Chestnut: 6.25% · Bay: 0% · Black: 93.75%

Example 3: Chestnut × Chestnut

Both parents ee → 100% Chestnut foals.

Real‑World Factors Influencing Coat Color

  • Additional dilution genes — Cream, dun, champagne, and silver can lighten base colors. This calculator focuses on base colors only.
  • Grey gene — A dominant modifier that causes progressive greying; a foal may be born a base color and turn grey over time.
  • White patterns — Tobiano, overo, sabino etc. add white markings but don't change the underlying base color genetics.
  • Hidden recessives — A black horse can carry a hidden chestnut allele (e), affecting foal probabilities.
  • Genetic testing — DNA tests provide exact genotypes, replacing the need for probabilistic prediction.

People Also Ask

It depends on the bay's genotype. If the bay carries a recessive chestnut allele (e), roughly 25% chestnut foals are possible. Most foals will be bay, with a small chance of black if both parents carry recessive a.
Yes, if both black parents are heterozygous (Eeaa) and both pass the e allele. The probability is 25% per foal in that specific cross.
Chestnut is recessive – it requires two copies of the e allele (ee). A horse with at least one E will produce black pigment and cannot be chestnut.
Agouti (ASIP) restricts black pigment to the points (mane, tail, lower legs). A dominant A allele plus at least one E results in bay. Without A (aa genotype) the horse is uniformly black.

Frequently Asked Questions

It gives mathematically exact probabilities based on the two‑gene model (Extension + Agouti). Real‑world coat color may be affected by additional modifiers not included here, so treat results as theoretical expectations.
No, the current version focuses on base colors only. Grey is a dominant modifier that can be added in a future update.
A visible color (e.g., Black) can be produced by different genotypes (EEaa or Eeaa). The calculator averages over all possible hidden allele combinations, assuming equal probability of each, to give a combined forecast.
Yes, the same Extension and Agouti genes apply across all equine breeds, from draft horses to miniatures.

Equine Color Genetics Glossary

Extension (E)

Gene that controls black pigment production. Dominant E enables black; recessive e restricts to red.

Agouti (A)

Gene that restricts black to points. Dominant A produces bay; recessive aa gives uniform black.

Genotype

The pair of alleles an individual carries (e.g., EeAa), which may differ from the visible color.

Punnett Square

A diagram used to predict the genotypes of offspring from a cross, showing all possible allele combinations.

Homozygous

Having two identical alleles for a gene (e.g., EE or ee).

Heterozygous

Having two different alleles (e.g., Ee). Can hide recessive traits.

Base Coat

The underlying color determined by Extension and Agouti: Chestnut, Bay, or Black.

Dilution

Genes like cream, dun, champagne that lighten the base coat. Not included in this basic calculator.

Editorial Review & Methodology

This equine color calculator was built and reviewed by the NumbrWiz Editorial Team based on established equine genetics principles (Extension & Agouti loci). The probability engine uses Mendelian Punnett‑square logic and assumes equal probability of hidden heterozygous states when the exact genotype is unknown.

  • Genetic model verification: Cross‑checked against standard equine genetics references (MC1R and ASIP loci).
  • Probability accuracy: All outcomes sum to 100% and reflect exhaustive genotype combinations.
  • Edge case testing: Verified with homozygous pairs, heterozygous hidden carriers, and combinations that produce 0% probability for certain colors.
  • UX review: Designed for clarity with immediate probability breakdown, copy/share functionality, and step‑by‑step genetic logic.

Transparency note: All calculations run client‑side in your browser. No data is ever collected, stored, or transmitted. Results are educational probability estimates – a DNA test provides definitive genotypes.

Page last reviewed: May 2026 · NumbrWiz Editorial Team