When is a Cornish Rex fully grown?

By approximately 12 months of age. Like most domestic cats, Cornish Rex cats reach their adult body size and weight within the first year, though muscle tone and coat continue to develop slightly into early adulthood.

How much should a Cornish Rex kitten weigh at 3 months?

Approximately 1–1.5 kg is typical at 3 months, though the breed's naturally slim build means individual variation is normal. Consistent week-on-week weight gain and healthy activity levels are more meaningful indicators than hitting a precise number.

My Cornish Rex kitten looks very thin. Is something wrong?

The Cornish Rex is naturally slender, and kittens look even leaner than adults. As long as the kitten is gaining weight week-to-week, eating well, and playing actively, lean appearance alone is usually normal. Any weight loss, stalled growth, or lethargy should be assessed by a vet.

Cornish Rex Growth Chart: What to Expect | PetCalculator

Cornish Rex kittens grow quickly and reach their adult size by around 12 months. This guide charts what healthy growth looks like month by month, what the breed's slim, arched physique means for interpreting weight milestones, and when to call the vet.