Article — Rabbit Color Genetics Calculator
Rabbit Color Genetics Calculator: Predicting Kit Coats
Rabbit color genetics is controlled by five major genes at separate loci. Four of them — A (agouti), B (black/brown), D (dense/dilute), and E (extension) — drive most coat variation. This calculator treats each locus as an independent Mendelian cross, multiplies the probabilities across all four, and reports the probability of every possible kit color from your parent genotypes.
Real rabbit color outcomes also depend on the C locus (full color, chinchilla, Himalayan, albino) and several minor modifier genes. The calculator simplifies by holding the C locus at full color, which captures the most common breeding situation. For chinchilla-line, Himalayan-line, or REW albino breeding, consult breed-specific tables for the full five-locus picture.
What rabbit color genetics controls
Rabbit color comes from two pigments: eumelanin (the dark pigment that can be black or brown) and pheomelanin (the light pigment, yellow to red). Every rabbit color is a combination of where these pigments deposit on the hair shaft, how dense they are, and whether eumelanin or pheomelanin dominates.
The four loci control different aspects. A controls the pattern (banded agouti vs solid self). B controls the eumelanin type (black vs brown). D controls density (full dense vs dilute). E controls extension of eumelanin (normal vs blocked, leaving only pheomelanin).
The A locus: agouti vs self
The A locus controls coat pattern. A (agouti) produces the wild-type banded coat with alternating bands of dark and light pigment on each hair, plus a lighter belly. at (tan) produces tan markings on muzzle, eye circles, belly, and inner legs. a (self) produces solid uniform color with no banding and no contrast.
Dominance order is A > at > a. Agouti dominates over both tan and self. Tan dominates over self. Two agouti parents (Aa × Aa) can produce self kits (aa) 25 percent of the time. Two self parents (aa × aa) can never produce agouti kits — the recessive aa cannot mask the dominant A.
The agouti pattern is named after the agouti rodent of Central and South America — the wild-type banded coat with light underside is the ancestral mammalian coat pattern. The same gene exists in mice, cats, dogs, and even some primates.
The B locus: black vs chocolate
The B locus controls which type of eumelanin the rabbit produces. B (black) is dominant and produces true black eumelanin. b (brown) is recessive and produces brown / chocolate eumelanin. The dominance is complete — BB and Bb both look black, only bb looks chocolate.
Two black rabbits (Bb × Bb) produce chocolate kits 25 percent of the time. A homozygous black (BB) crossed with chocolate (bb) produces all heterozygous black (Bb) offspring that all look black but carry chocolate as a hidden recessive. This is how chocolate disappears for a generation and reappears in the next.
The D locus: dense vs dilute
The D locus controls pigment density. D (dense) is dominant and produces fully saturated pigment. d (dilute) is recessive and lightens the pigment uniformly. Black plus dilute (aa B_ dd) becomes blue — a slate gray. Chocolate plus dilute (aa bb dd) becomes lilac — a dove gray.
Dilute is the most common recessive in rabbit color genetics. Many breed standards include both dense and dilute versions of the same base color (black/blue, chocolate/lilac, red/cream, tortoise/pale tortoise). Two dense-color rabbits with one d allele each (Dd × Dd) produce 25 percent dilute kits.
Dilute coat color comes with subtle physical differences. Dilute rabbits often have slightly lighter eye color (gray-blue rather than dark brown) and the hair shaft itself is structurally different. Breeders use these as confirming traits when DNA testing is not available.
The E locus: extension
The E locus controls whether eumelanin extends into the hair shaft. E (normal extension) is dominant and allows full eumelanin expression. e (non-extension) is recessive and blocks eumelanin, leaving only pheomelanin (yellow-red surface pigment).
The ee genotype produces dramatic color changes. Black-based ee becomes tortoise (yellow body with sooty face, ears, and feet). Agouti-based ee becomes red or orange. Dilute ee becomes cream or pale tortoise. Even chocolate-based ee looks similar to black-based ee — the B locus is masked when E pigment is absent because there is no eumelanin to differentiate.
Combining four loci into rabbit color
The phenotype mapping across all four loci produces 12 commonly recognized rabbit colors when the C locus is held at full color. The calculator computes the probability of each color by multiplying single-locus probabilities under independent assortment.
- A_ B_ D_ E_ = Chestnut Agouti (wild type)
- A_ B_ dd E_ = Opal (blue agouti)
- A_ bb D_ E_ = Chocolate Agouti
- A_ bb dd E_ = Lynx (lilac agouti)
- aa B_ D_ E_ = Black
- aa B_ dd E_ = Blue
- aa bb D_ E_ = Chocolate
- aa bb dd E_ = Lilac
- A_ _ _ _ _ ee = Red, Orange, or Cream
- aa _ _ _ _ ee = Tortoise or Pale Tortoise
Hidden recessive carriers
Two black rabbits can produce kits of nearly any color if both carry hidden recessive alleles. A black rabbit might be aa Bb Dd Ee — carrying chocolate, dilute, and non-extension recessives all at once. Crossed with another rabbit of the same genotype, the litter can include black, chocolate, blue, lilac, tortoise, and pale tortoise kits, in proportions predicted by the calculator.
Phenotype reveals only the dominant alleles. The way to expose hidden recessives is the test cross — pair the unknown to a fully recessive partner. Recessive offspring confirm the unknown was a carrier. Commercial breeders test-cross potential breeding stock before introducing them to the main herd to avoid surprise colors and breed-standard disqualifications.
You cannot tell from a single rabbit whether it carries hidden recessives without either DNA testing, pedigree analysis, or test crossing. A litter of 8 black kits from black parents proves nothing about hidden alleles — it could simply mean the recessives did not happen to show up in this particular litter.
Planning a rabbit color cross
Start with the genotype each parent. If only phenotype is known, treat the dominant trait as uncertain — could be homozygous or heterozygous. Show breeders typically know parent genotypes from documented pedigree going back several generations.
Enter parent genotypes into the calculator one locus at a time. The output is a complete probability table of every possible kit color. Plan around the most likely outcomes, but expect the unexpected — small litters routinely deviate from predicted ratios, and a 25 percent prediction does not guarantee one kit in four of that color.
A_ B_ D_ E_ chestnut agoutiaa B_ D_ E_ blackaa B_ dd E_ blueaa bb dd E_ lilac_ _ _ _ ee tort / red / cream