When Do Cats Stop Growing?

What is the typical growth timeline?

Most domestic shorthair and medium-sized cats follow a predictable pattern. Rapid growth happens during the first six months, when kittens gain weight quickly and hit major developmental milestones. Growth slows between 6 and 12 months as the cat approaches adult proportions. Most average-sized cats reach their full height by 12 months and finish filling out in muscle and body mass by 18 months. After that point, any additional weight gain is typically fat rather than growth, which is an important distinction for monitoring healthy body condition.

Why do large breeds take so much longer?

Maine Coons, Ragdolls, Norwegian Forest Cats, and other large breeds have a significantly extended growth period. Maine Coons are the most extreme example, often not reaching full size until 4 to 5 years of age. Their skeletal frame, muscle mass, and coat all continue developing well past the point where an average cat has finished growing. This slow maturation is genetically programmed; these breeds are simply built on a larger blueprint that takes longer to complete. Feeding a large-breed kitten appropriately during this extended growth phase is important for proper bone and joint development.

Does spaying or neutering affect growth?

Yes. Cats that are spayed or neutered before reaching full maturity (typically before 6 months) may grow slightly taller than intact cats. This is because sex hormones signal the growth plates in bones to close, and removing those hormones through early sterilization delays that closure, allowing the bones to grow slightly longer. The difference is modest and not a health concern. Spayed and neutered cats are also more prone to weight gain due to metabolic changes, so monitoring food intake after the procedure helps prevent the growth in size from becoming growth in fat.

How can you tell if your cat is still growing?

Regular weigh-ins are the simplest method. A cat that is still gaining weight gradually (not suddenly) on a consistent diet is likely still growing. Physical proportions offer clues as well; adolescent cats often look slightly lanky with legs that seem too long for their body before they fill out. If your cat's paws look disproportionately large compared to their frame, they probably have more growing to do. Your vet can assess skeletal maturity through physical examination. Once a cat has maintained a stable weight for several months on a consistent diet, they have likely reached their adult size.