🧬 Kitten Coat Colour Predictor
Why are orange cats mostly boys? Why are calicos almost always girls? Why did two black cats just produce a grey kitten? Coat genetics has rules — pick the parents and watch the kittens' possible colours fall out, daughters and sons separately.
The parents
♀ Mother (queen)
♂ Father (tom)
Fathers can't be tortoiseshell (outside of rare XXY exceptions) — which is itself one of the fun results below. Orange parents always show ghost tabby markings, whatever the pattern gene says — nature insists.
The kittens could be…
♀ Daughters
♂ Sons
Probabilities are per kitten of that sex, and assume — as predictors must — that solid-coloured parents aren't hiding carrier genes. The notes below flag exactly where a hidden carrier could add a surprise colour.
Why use this predictor?
The orange gene explains the internet's favourite cats
Orange lives on the X chromosome. Boys need one copy to be orange; girls need two — hence ~80% of orange cats are male, and an orange mother passes orange to ALL her sons. Run an orange mum through the predictor and watch the sons' column go solid orange.
Percentages, not just possibilities
"Could be black or tortie" is trivia; "50% tortie, 50% black" is a prediction. Every outcome here carries its Mendelian probability per sex — the same maths breeders use when planning a litter, minus the guesswork.
It works backwards, too
Found a litter and wondering who the father was? The kittens' colours testify: a chocolate kitten means BOTH parents carried chocolate; a tortie daughter means her father was orange or her mother was tortie. Shelter staff use exactly this logic.
The seven genes, in plain language
| Gene | What it does |
|---|---|
| Orange (O) — X-linked | Swaps dark pigment for orange. One copy in a female = tortoiseshell (both colours show, cell by cell); two = fully orange. Males have one X, so they're orange or not — never tortie. |
| Black family (B) | Sets the dark pigment shade: black (dominant) → chocolate → cinnamon (most recessive). Recessive shades appear only when both parents pass them. |
| Dilution (D) | Two copies of dilute "water down" any colour: black→blue, chocolate→lilac, cinnamon→fawn, orange→cream. One copy does nothing visible — it just hides. |
| Agouti (A) | Tabby pattern on/off. Non-agouti (aa) = solid colour. Orange overrides it visually — every orange cat shows stripes regardless. |
| White spotting (S) | Adds white patches — more copies, more white. It's what turns a tortoiseshell into a calico, and a black cat into a tuxedo. |
| Dominant white (W) | One copy paints the whole cat white, hiding every other gene underneath. (Also the gene behind most blue-eyed, sometimes deaf, white cats — worth a vet chat, not a worry spiral.) |
| Colourpoint (cs) | The Siamese pattern: pigment only where the body is coolest (face, ears, paws, tail). Needs two copies — one from each parent. |
Questions people ask
Can a male cat be a calico?
About 1 in 3,000 — and he's a genetics headline: calico needs two X chromosomes (one carrying orange, one not), so a male calico is almost always XXY. Such males are nearly always sterile. If your "male calico" is a proud father, he's either the rarest of exceptions or (much more likely) she's a girl.
Two black cats had a grey (blue) kitten. Is that possible?
Completely — both parents were black but carried hidden dilution (Dd). The kitten drew dilute from both: one-in-four odds per kitten, on average. This is the #1 "the father must be someone else!" false alarm in cat breeding. Genetics says otherwise.
Why do all the kittens look different from both parents?
Because each parent carries a hidden hand: recessive genes (chocolate, dilution, points, solid) can pass silently for generations and then meet in one kitten. Add X-linked orange dealing different cards to sons and daughters, and a litter of four can look like four different families.
Does the predictor work for purebred breeding?
The colour maths is the same — but breeders also track what this tool deliberately leaves out: silver/smoke, sepia (Burmese) and mink (Tonkinese) colour restriction, wide-band tabby effects, eye colour, and breed-specific recessives. Use this for the classic seven loci; use a breed geneticist (and DNA tests) for the rest.
What colour eyes will the kittens have?
All kittens are born with blue eyes; true eye colour develops from ~6–12 weeks and follows its own genetics (loosely linked to coat: pointed and white cats often keep blue). It's not predicted here because it's far less deterministic than coat colour.
Keep exploring
Pregnancy Calculator — if these kittens are already on the way · Cat Name Generator — a litter needs names · Kitten Growth Predictor — for after they arrive · All KittyButts tools
A simplified, deterministic model of the seven best-known coat loci, assuming non-carrier parents where a gene can't be seen. Real litters add hidden carriers, rarer loci and the odd genetic surprise — which is half the fun. For fun and education, not a breeding guarantee.