When Do Dogs Stop Growing?
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Puppies grow fast—it almost seems like you can see it every day. But they can’t keep growing forever, which raises the question: When do dogs stop growing? And how big will your puppy get?
Here’s what to know.
Key Takeaways
- Breed is the biggest factor in determining when a dog is finished growing.
- Pet parents have some control over certain factors that influence growth, including nutrition and when a dog is spayed or neutered.
- Small breeds grow more quickly and for a shorter amount of time.
- Large dog breeds take a longer time to reach their adult size.
What Affects a Dog’s Growth?
Many factors determine a dog’s growth and ultimate size. Some we have some control over, but others are determined by nature:
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Breed: Breed is the biggest factor in determining both growth rate and when a dog reaches their mature size. Small dog breeds become full-grown sooner than large dog breeds.
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Genetics: A dog’s genetics set the baseline for their size and how fast they grow.
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Nutrition: Dogs who are fed an inadequate food, or who are fed too little or too much, can have unwanted changes in their growth rate and develop lifelong growth deformities.
When Do Dogs Stop Growing?
Generally, small breeds grow more quickly and for a shorter period of time than large dogs.
| Dog Size | Typical Age When Fully Grown |
|---|---|
| Toy (5–12 pounds) | 8–12 months |
| Small (12–24 pounds) | 9–12 months |
| Medium (24–59 pounds) | 12–15 months |
| Large (59–99 pounds) | 15–18 months |
| Giant (over 100 pounds) | 18–24 months |
Although all dogs are a little different, a puppy stops growing when the actively producing part of the bone (called a growth plate) seals, stopping growth processes.
How Big Will My Puppy Get?
While we can never know for certain how big a puppy will get, veterinarians can take an educated guess.
Estimating the size of purebred puppies is the most accurate, since the adult weight ranges are generally consistent across a breed. For mixed-breed dogs, the question of size gets more complicated.
If a DNA analysis is available for the pup, this can help improve accuracy. Otherwise, veterinarians rely on factors like the size of the puppy’s parents (if known) and physical traits like paw size, leg length, body build, and sex.
Veterinarians can sometimes also help estimate size by palpating the bone structure of your pup or checking X-rays to see if the growth plates have closed. (Once these close, growth is mostly finished.)
How To Tell When a Dog Is Fully Grown
The best way to tell when dogs are fully grown is by checking the growth plates with an X-ray.
Though it’s hard to determine without an X-ray, generally your pup is done growing if they have reached the age category in the table shown above and don’t seem to be increasing in size.
Talk to your veterinarian about how to care for your dog once they approach their fully grown size. If you guess that your dog is done growing sooner than they truly are, adjusting parts of their care (such as switching from puppy to adult food) can hinder normal growth.
Some basic weight formulas can be used for a general estimate if the age of the pup is known:
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For small and toy breeds, multiply the puppy’s weight at 6 weeks old by 4 or their weight at 8 weeks old by 3. This hints at their estimated adult weight.
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For medium to large breeds, multiply the puppy’s weight at 4 months of age by 2 for an estimate.
Caring for a Growing Puppy
Often, the biggest influence on normal puppy growth comes from good care: a proper diet in the right amounts, balanced with the correct amount of exercise.
Nutrition
Proper nutrition is critical—especially ensuring that the pup is eating the correct formula in the right amounts.
Puppy-specific dog foods are high in fat, protein, and calories to support growth. There are also large-breed puppy formulas designed to stop your puppy from growing too quickly, which can damage growing joints and bones.
Poorly formulated foods can result in stunted growth, weakened bones, and health problems including hip dysplasia. Overfeeding your dog can also damage the bones and joints by placing more weight on them than they can handle.
Exercise
Exercise also plays a role in muscle development and joint health.
Puppies need regular activity, but not overexertion—especially large-breed puppies. Too much jumping or running early on can stress growing joints and bones. Providing a balanced exercise plan supports healthy growth without injury risk.
Health Issues
Underlying health issues can also interfere with normal growth. Most common would be issues with parasites such as:
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Intestinal worms, which can steal nutrients and stunt growth
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Chronic illnesses that slow growth and affect immune function
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Injuries to the growth plates, which can result in uneven or improper limb development.
Spaying and Neutering
The age of spaying and neutering can also influence the time when the growth plates close. This needs to be balanced with the potential risks (such as mammary cancer) that are avoided by spaying early in life.
Talk to your veterinarian to determine the best time for your pup to be spayed or neutered.
Your veterinarian will check the growth rate of your pup with each wellness visit. If your pup does not seem to be growing normally, is gaining weight too quickly, or seems to have pain in the bones or joints, this can indicate a growth problem.
