How the calculator works
Each gene is worked out on its own, just like a monohybrid cross. For seven of the genes, both parents pass on one of their two alleles, so each gene gets a 2×2 Punnett square. The Orange gene is on the X chromosome, so it gets an X-linked square: daughters receive the father’s X, sons receive his Y.
The calculator then combines the genes with the product rule. If ½ of daughters are tortoiseshell and ¼ of kittens are dilute, then ½ × ¼ = ⅛ of daughters are dilute tortoiseshell (blue-cream). That’s the same idea as the no-Punnett-square method for trihybrid crosses.
The genes in the calculator
| Gene | Alleles (dominant first) | What it does |
|---|---|---|
| Orange (X-linked) | O, o | Orange vs black-based pigment. One of each in a female gives tortoiseshell patches. |
| Brown (TYRP1) | B > b > bl | Black, chocolate or cinnamon. |
| Dilute (MLPH) | D, d | d/d: black → blue, chocolate → lilac, cinnamon → fawn, orange → cream. |
| Agouti (ASIP) | A, a | A lets tabby stripes show; a/a is solid (except on orange fur). |
| Tabby pattern (TAQPEP) | Mc, mc | Mackerel (striped) vs classic (blotched) tabby. |
| White (KIT) | W > S > w | W: all-white coat that hides every other color gene. S: white patches, usually more with two copies. Tortie + white = calico. |
| Colorpoint (TYR) | C > cb = cs | cs/cs: Siamese points; cb/cb: Burmese sepia; cb/cs: mink. |
| Hair length (FGF5) | L, l | l/l: long hair. |
What the calculator simplifies
- Fewer alleles than real cats have. For example, there are several long-hair variants of FGF5, an albino allele at the colorpoint gene, and other white and pattern genes not included here.
- Coat names. Results use registry color terms with the everyday word in brackets: red (orange), blue (gray), lilac (pale pinkish gray), seal (dark brown), lynx (tabby) point, blue-cream (dilute tortoiseshell). Registries differ on some names and on how much white a coat needs to count as “with white”, and the clarity of tabby stripes and the shade of points vary from cat to cat.
- Independent genes. Each gene is treated as inherited independently of the others.
- Normal sex chromosomes. Kittens are XX or XY with equal chance. Rare XXY males and chimeras aren’t modeled.
- Probabilities, not promises. A ¼ chance means each kitten has a 1 in 4 chance, not that exactly one kitten in four will have that coat.
A visible example of genes meeting environment: the Siamese cs allele makes a heat-sensitive enzyme, so dark color develops only on the cooler ears, face, paws and tail. Read more in beyond Mendelian inheritance.
Frequently asked questions
Can this calculator tell me what color my kittens will be?
It gives the probabilities for each coat type, assuming you know (or can guess) both parents’ genotypes. It can’t promise a particular litter: each kitten is a separate chance event, and real cats vary more than any coat name suggests. A DNA test from a veterinary genetics lab is the most direct way to find hidden alleles; a cat’s offspring can also reveal them.
Why are the results split into female and male kittens?
The Orange gene is on the X chromosome. Daughters inherit an X from each parent; sons inherit their only X from their mother. That’s why tortoiseshell and calico kittens are almost always female. See why calico cats are almost always female.
How do I find a cat’s genotype from its color?
A visible color tells you some alleles for certain. A blue (gray) cat must be d/d; a solid-colored cat that isn’t orange or white must be a/a; a long-haired cat must be l/l; a non-white male’s Orange allele is shown by his coat. Hidden recessive alleles (such as a black cat carrying dilute) only show up in offspring or in a DNA test.
Why does an orange cat show tabby stripes even when it is non-agouti (a/a)?
Orange pigment cells don’t respond to the agouti gene in the usual way, so orange fur often shows tabby (sometimes faint "ghost") markings regardless. The calculator names red (orange) coats as tabby for this reason.
Are white cats deaf?
Some are. The dominant white gene (W) is linked with a higher chance of deafness, especially in white cats with blue eyes, but many white cats hear normally. A vet can test hearing with a BAER test. The calculator only predicts coat color.
Does the calculator model male calico cats?
No. Male calicos and tortoiseshells are rare and usually have an extra X chromosome (XXY) or are chimeras. The calculator uses the normal XX and XY model, so it never shows tortoiseshell sons.
Sources
- UC Davis Veterinary Genetics Laboratory, Feline coat color.
- Kaelin CB, et al. “Molecular and genetic characterization of sex-linked orange coat color in the domestic cat.” Current Biology (2025). doi:10.1016/j.cub.2025.04.055
- David VA, et al. “Endogenous retrovirus insertion in the KIT oncogene determines white and white spotting in domestic cats.” G3 (2014). doi:10.1534/g3.114.013425
- Schmidt-Küntzel A, et al. “Tyrosinase and tyrosinase related protein 1 alleles specify domestic cat coat color phenotypes of the albino and brown loci.” Journal of Heredity (2005). doi:10.1093/jhered/esi066
- Ishida Y, et al. “A homozygous single-base deletion in MLPH causes the dilute coat color phenotype in the domestic cat.” Genomics (2006). doi:10.1016/j.ygeno.2006.06.006
- Kaelin CB, et al. “Specifying and sustaining pigmentation patterns in domestic and wild cats.” Science (2012). doi:10.1126/science.1220893
- Drögemüller C, et al. “Mutations within the FGF5 gene are associated with hair length in cats.” Animal Genetics (2007). doi:10.1111/j.1365-2052.2007.01590.x