How is horse coat color inherited?

Horse coat color is determined by multiple genes that interact. The Extension (E) gene controls black vs. red pigment, Agouti (A) affects black pigment distribution (bay vs. black), and Cream (Cr), Gray (G), and other genes create dilutions and patterns. Each parent passes one copy of each gene to the foal. Colors are predictable using Punnett squares when you know parent genotypes.

What is the difference between genotype and phenotype?

Genotype is the genetic code a horse carries (which alleles they have), while phenotype is the visible coat color. For example, a bay horse could be genetically EE/AA (homozygous bay) or Ee/Aa (heterozygous bay) - different genotypes produce the same phenotype. Knowing genotypes allows accurate breeding predictions, while phenotype alone sometimes leaves uncertainty about genetics.

Can two chestnut horses have a non-chestnut foal?

No, two chestnut horses (genotype ee) can only produce chestnut foals because chestnut is recessive. Both parents can only pass the 'e' allele, so all foals are ee. However, the foal could be a diluted chestnut (palomino, cremello) if dilution genes are present, or appear different shade/pattern, but will have red-based coloring without black points.

What colors can a bay and chestnut horse produce?

A bay horse carries at least one Extension gene (E) for black pigment and Agouti gene (A) that restricts black to points. If the bay is Ee/Aa (heterozygous), bred to chestnut (ee/aa), foals can be bay (25%), chestnut (25%), black (if Ee/aa - 25%), or theoretically seal brown (with certain Agouti combinations). If the bay is EE/AA, all foals will be bay.

Why do some horses change color as they age?

The Gray gene (G) causes progressive graying, where horses are born a dark color and gradually lighten to gray or white over years. Gray is dominant - one copy from either parent causes graying. Born-gray horses don't exist; all start colored and gray out. Other genes like Rabicano or Roan can cause gradual color changes. Without genetic testing, these modifiers can complicate color predictions.

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Horse Coat Color Calculator

Predict the probability of foal coat colors based on sire and dam genetics.

Sire (Father)

Dam (Mother)

Possible Foal Colors

* Note: This is a simplified prediction based on phenotypes. Actual probabilities depend on the specific genotype (Agouti/Extension status) of the parents.

How to Use This Calculator

Select Sire's Color and Genes

Choose the stallion's visible coat color (phenotype), and if known, his specific genotype (genes carried). Genetic testing provides precise genotypes for accurate predictions.

Select Dam's Color and Genes

Choose the mare's visible coat color and genotype. If exact genotype is unknown, the calculator can work with phenotype-based probabilities, though results will be less certain.

Include Dilution/Pattern Genes

Add any dilution genes (cream, dun, champagne), pattern genes (roan, gray, tobiano, overo), or other modifiers carried by either parent if known.

View Foal Color Probabilities

See the possible foal colors with percentage probabilities for each outcome. Results show both the most likely colors and rare possibilities based on recessive genes.