When Do Puppies Stop Growing?

Small breeds (under 20 lbs)

Chihuahuas, Yorkshire Terriers, Pomeranians, Maltese, and other toy or small breeds finish growing relatively quickly. Most reach their adult size between 9 and 12 months of age. They typically hit their adult weight by around 9 months and then fill out slightly over the next few months. Because they have less growing to do, small breeds mature faster overall and can often switch from puppy food to adult food by their first birthday.

Medium breeds (20 to 50 lbs)

Beagles, Cocker Spaniels, Border Collies, and similar medium-sized breeds typically finish growing between 12 and 15 months. They hit most of their adult size by around 12 months and then add some muscle and fill out over the next 3 to 6 months. Medium breeds often look gangly and adolescent longer than small breeds because they grow over a longer period.

Large breeds (50 to 90 lbs)

Labrador Retrievers, Golden Retrievers, German Shepherds, and Boxers generally take 15 to 18 months to finish growing. Their bones and joints continue developing into their second year, which is why large breeds are typically kept on large-breed puppy food longer than smaller dogs. Feeding a large breed an adult diet too early can actually contribute to joint problems by encouraging too-rapid growth.

Giant breeds (over 90 lbs)

Great Danes, Saint Bernards, Mastiffs, Newfoundlands, and Irish Wolfhounds can take 18 months to 2 years or longer to reach full size. Their skeletal development is slower and more prolonged to support their eventual massive frames. Giant breeds are particularly vulnerable to developmental orthopedic diseases, so careful nutrition and controlled exercise during growth are critical. According to the American Kennel Club, feeding giant-breed puppies an appropriately formulated large-breed puppy food and avoiding high-impact exercise is essential during this extended growth period.