When do kittens stop growing?

Kittens stop growing once they reach full adulthood, depending on their breed and genetic profile, but some breeds can have explosive growth spurts in the first four years of life, such as the Ragdoll, according to The Cat Fancier's Association Complete Cat Book. Most cats reach adulthood by 10 months of age.

Kittens begin their independent life around 6 to 8 weeks of age when they start to eat, drink and move around their environment on their own. The domestic cat, when fully grown, can weigh anywhere from 5 to 20 pounds, depending on the breed and genetic makeup of the cat.