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Puppies seem to grow up so fast. One day, they’re little balls of furry cuteness and, in what seems like the blink of an eye, they’re fully grown into loving companions. But not all dogs grow at the same rate, with smaller breed dogs growing up much faster than their larger counterparts. That’s because those bigger bones and joints need a bit more time to grow and develop.
Puppies, especially those of a larger breed, have special dietary and exercise requirements to consider while they are still growing. And, once pups are fully grown, you’ll know just how big or small they’ll be, so you can buy them all the essential dog supplies they’ll need in the correct sizes, like crates, collars, beds, and protective jackets. That’s why it’s so important to know just when your puppy will finish growing.
Puppy Growth Chart By Percentage
All numbers are approximate. Consult your veterinarian if in doubt.
Small (0-20 lbs)
Medium (21-50 lbs)
Large (51-100 lbs)
X-Large (100+ lbs)
6 months
75% fully grown
66%
60%
50%
9 months
90%
85%
75%
65%
12 months
100%
95%
85%
80%
15 months
100%
100%
95%
90%
18 months
100%
100%
100%
100%
How Long Do Puppies Grow?
Although all puppies are officially considered adult dogs once they reach 1 year old, puppies continue to grow in height and size while their bones are still developing, which takes anywhere from 6 to 24 months. Their skeletal growth is what determines how tall they’ll become as adults.
“The long bones in a puppy’s legs grow from two distinct places called growth plates,” according to Dr. Jerry Klein, DVM and Chief Veterinarian for the AKC. “The growth plates are somewhat flexible and soft during puppyhood when new tissue is being formed.”
As your puppy grows, the new tissue developed hardens into bone. “When the growth plates have stopped producing new tissue and become completely calcified, they are said to have ‘closed,’ which means that they’ve stopped growing and the bone has reached its final size,” says Dr. Klein.
Keep in mind, even after the bones are fully developed, your puppy will continue to develop fat and muscle, just as human adults do.
When Do Smaller Puppy Breeds Finish Growing?
Small and medium puppy breeds grow up pretty quickly. In fact, those petite puppies finish growing at around half the age of their larger counterparts, according to Dr. Klein. “On average, small breeds typically stop growing by the time they reach 6 to 8 months of age.”
Medium breed puppies might take just a bit longer to grow, reaching their adult size at around 12 months of age.
When Do Larger Puppy Breeds Finish Growing?
A larger dog takes a bit more time than a smaller one to reach full adult size because those bigger bones need more time to grow. “Giant breed puppies grow until they are 12 to 18 months old,” says Dr. Klein.
Large to giant breed puppies usually weigh 70 or more pounds as adults. In some cases, very large breeds like Mastiffs may not even reach their fully grown size until 24 months of age.
When Do Purebred Puppies Finish Growing?
If you’ve recently acquired a purebred AKC-registered puppy, then the breeder can let you know approximately how large your puppy will get and the expected growth rate based on their experience with other members of the puppy’s family tree.
“Purebred dogs are known first and foremost for their predictability: predictability of size, coat, temperament, etc.,” says Dr. Klein. “Granted, there will be variances within members of each breed (and each litter), but generally speaking, the breed can certainly help determine final size at adulthood.”
When Do Mixed-Breed Dogs Finish Growing?
For mixed-breed puppies, determining their growth rate can be a little more tricky. “When dealing with a dog of unknown heritage, it becomes a bit of a guessing game as to determining the final size,” says Dr. Klein. This is especially true for younger puppies between 6 and 10 weeks of age.
“A helpful hint is that if you run your hands down a dog’s rib cage and you can still feel the ‘knobs’ of the ribs, that dog will probably continue to grow in height,” recommends Dr. Klein. That’s because these “knobs” are the growth plates of the ribs that are still developing.
How Do I Feed a Growing Puppy?
Foods that meet the nutritional guidelines set up by the Association of American Feed Control Officials (AAFCO) and are specifically designed for all life stages will provide your developing puppy all the nutrition they need. These foods also don’t require a transition onto an adult-specific food once they’re fully grown.
“Those foods designated for ‘all life stages’ mean that they meet needs of both growing and adult animals,” according to Dr. Klein. You’ll also find puppy-specific foods that ensure your dog gets all the nutrients they need, but you’ll only want to feed those until adulthood — around 11 to 14 months of age.
Most importantly, always follow the guidelines on the food when feeding your puppy so they don’t become overweight. “It is known that obesity in puppies can lead to a predisposition of future orthopedic issues later in life, such as hip dysplasia, so a fit, leaner puppy is considered preferable to a chubby older puppy,” warns Dr. Klein.
How Do I Feed Large and Giant Breed Puppies?
Too much calcium in your large or giant breed puppy’s diet isn’t good for their development, warns Dr. Klein. “This is because large and giant breeds are more sensitive than smaller ones to an excess or shortage of calcium while their bones are growing,” says Dr. Klein.
When shopping for food for your large-breed puppy, look for pet food labels that read “[Pet Food Name] is formulated to meet the nutritional levels established by the AAFCO Dog Food Nutrient Profiles for growth or all life stages including growth of large-size dogs (70 lbs or more as an adult),” recommends Dr. Klein.
How Do I Exercise Growing Puppies Safely?
Puppies are little balls of energy who need exercise to stay healthy, but too much exercise isn’t good for puppies. “It is imperative to know that excessive, prolonged activity, like jogging, can be extremely detrimental on the bones and joints of growing puppies,” warns Dr. Klein.
“This is why it is never recommended to do road work or jogging on a dog less than 14 to 18 months of age, especially large and giant breeds, until the growth plates have fully fused,” says Dr. Klein. Instead, walk moderately short distances of a quarter-mile or less on softer surfaces like grass or sand until your dog has finished growing.