Signs a Pup Is Fully Grown

Most canines reach their full size by the time they are 12 to 18 months old, although it does take longer for some of the largest breeds to finish growing. Some breeds even reach a full frame within the first six months of life, although it takes longer for the rest of the body to catch up. Here's a general guideline that will show you when you can expect your puppy to stop growing.

Small Breeds

These pups tend to reach their full-sized framework between six and eight months old, and they'll typically fill out to their full weight by 12 months old.

Medium Breeds

You can expect breeds that fall into this group to reach their full-sized framework between 12 and 15 months old, but they usually won't reach their full weight until they're closer to 18 months old.

Large Breeds

This group is slower growing, and most large puppies won't reach their full-sized frame until 15 to 18 months old and their full adult weight until they're about two years old.

Giant Breeds

Dogs like Mastiffs, Great Pyrenees, Saint Bernards and Newfoundlands take the longest to reach full size. Their basic framework is in place by about 18 months old, but it can take until age two or three for them to reach full weight and muscle mass.