If you have ever wondered what color foal you might get from a planned breeding, this horse color genetic calculator gives you a fast, practical estimate. Select each parent’s genotype for the key loci below and the tool calculates expected probabilities for common coat outcomes.
Interactive Horse Color Genetic Calculator
This calculator models four major loci: Extension (E/e), Agouti (A/a), Cream (N/Cr), and Gray (G/g).
Parent 1
Parent 2
Note: Gray is a dominant modifier and can mask the foal’s underlying base color over time.
How this horse coat color calculator works
This tool applies classic Mendelian inheritance using Punnett-square logic for each selected gene. For every locus, it computes the possible offspring genotypes and their frequencies. Then it combines those independent probabilities across all loci to generate estimated phenotype outcomes.
The output is most useful when both parents are DNA tested. If a parent’s genotype is unknown and you are guessing from visible color alone, results may differ in real life.
Quick primer on the included genes
1) Extension (E/e) – black vs. red pigment production
The Extension gene controls whether black pigment can be produced.
- e/e: red base only (chestnut family).
- E/_: black pigment is possible (then Agouti decides distribution).
2) Agouti (A/a) – where black pigment is placed
Agouti only matters when the horse has at least one E allele.
- A/_: black pigment restricted to points (bay family).
- a/a: unrestricted black pigment (black family).
3) Cream (N/Cr) – dilution intensity
Cream dilution has a dosage effect:
- N/N: no cream dilution.
- N/Cr: single cream dilution (palomino, buckskin, smoky black).
- Cr/Cr: double cream dilution (cremello, perlino, smoky cream).
4) Gray (G/g) – progressive depigmentation
Gray is dominant. Foals with G/_ are born with a base color but typically lighten over time. This is why the calculator reports gray outcomes with the hidden base color noted in parentheses.
What the result table means
Your main table shows estimated probabilities for final visual color classes from the modeled genes. For breeders and owners who want deeper detail, the calculator also provides genotype probability tables by locus so you can see possible genetic outcomes behind those visual colors.
Example use case
Suppose both parents are E/e, A/a, N/Cr, g/g. The foal can land in chestnut-, bay-, or black-based families, with additional cream dilution outcomes. Since both are non-gray, gray probability will be zero. This kind of scenario is common when breeding for buckskin or palomino while keeping other possibilities in mind.
Important limitations
This calculator intentionally focuses on four major loci for clarity. Real horse color prediction can involve many additional genes and modifiers, such as:
- Dun
- Silver
- Champagne
- Pearl
- Roan
- Tobiano and other white pattern genes
- Sooty, flaxen, and polygenic influences
So think of this as a practical planning tool, not a full lab-grade genomic simulator.
Bottom line
If you combine this calculator with reliable DNA testing, you can make much better breeding predictions and set realistic expectations for foal color outcomes. It is fast, transparent, and useful for both new horse owners and experienced breeders.