When is the cat done growing?
Even though many cats stop growing at 12 months, not all cats are done growing at this age. But if they are still growing, it will be at a much slower rate, generally from 12-18 months, so you can expect your cat to be very close to their full adult size at this point.
The growth rate of cats varies depending on the breed, but in general, cats reach their full physical maturity between one and two years of age. While their physical growth will be completed by this time, their personalities and socialization will continue to develop throughout their lifetime.