Cornish Rex — Color Genetics & EMS Calculator

The Cornish Rex is defined by a distinct recessive rexoid mutation (r) at a locus non-allelic to the Devon Rex gene (re), resulting in a fine, wavy coat with reduced awn and guard hairs that expresses all pigmentation genotypes normally in terms of EMS color classification. FIFe standard accepts all colors and patterns for CRX, spanning the full B-locus allelic series, colourpoint (cs/cs) variants, all tabby patterns, and the O-locus tortie combinations, placing identical demands on feline genetics program management as DRX. An EMS color calculator for Cornish Rex breeders should flag the non-allelism of r and re as a first-line outcross compatibility check, since CRX × DRX matings produce entirely straight-coated F1 offspring.

Cornish Rex colour genetics: frequently asked questions

Which recessive colours do Cornish Rex cats commonly carry?
The r allele is recessive; heterozygous (R/r) cats are straight-coated. All color recessives (b, bl, d, cs) are present in CRX populations. The Cornish Rex has historically undergone outcrosses to British Shorthair, Siamese, and other breeds, introducing a broad allelic diversity across color loci.
What colour restrictions apply to the Cornish Rex breed standard?
No color or pattern restrictions apply. The r allele is non-allelic to the Devon Rex (re) and the German Rex (rg) — crosses between these breeds produce straight-coated double heterozygotes. Dominant White (W) is accepted. Amber (e) is not specifically listed in FIFe CRX standard.
Which coat patterns are typical for the Cornish Rex?
All tabby patterns (22, 23, 24, 25) are accepted. The reduced coat structure of the Cornish Rex may render tabby pattern contrast less visually distinct compared to full-coated breeds, but phenotypic assessment for EMS coding follows standard rules.

Popular EMS Colors

CRX nBlack (solid)
CRX a 25Blue Ticked Tabby
CRX bChocolate (solid)
CRX f 23Black Tortie Mackerel Tabby
CRX n 33Seal Colourpoint
CRX ns 22Black Silver Classic Tabby

Calculate Colors for Cornish Rex

Free online cat color genetics calculator. Select the breed and appearance of the sire and dam to predict kitten coat colors, patterns and probabilities based on feline color genetics.

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Enter the appearance of both parents to calculate color predictions.

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