Most cats: around 10 to 12 months
Growth is fastest early in kittenhood, then slows. Veterinary nutrition guidance notes that many kittens reach adult body size at about 40 weeks and mature around 10 to 12 months. Large breeds can continue developing for longer, sometimes to about 18 months.
Breed is only part of the answer
Genetics, sex, neuter status, nutrition and health all influence the curve. Healthy growth is not the same as maximum-speed growth: overfeeding can add body fat without making bones and muscles mature more appropriately.
Regular weights and body-condition checks are more informative than comparing one kitten with a friend’s cat of the same age.
Growing out of kitten food
Kittens need food formulated for growth. The transition to an adult diet is commonly considered at about one year or once maturity is reached, whichever is later. Ask a veterinarian when breed, body condition or a health condition makes the timing less obvious.
Sources and further reading
Sources support the general information on this page. CatMind is an observation tool, not a veterinary diagnostic service.
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