When puppies reach their full adult size depends primarily on their breed. Small breeds generally reach adult size between 10-15 months. Medium breeds reach adult size between 12-16 months. Large and giant breeds take even longer, sometimes up to 2 years to reach their full adult size.
When are small breed puppies fully grown?
Small breed puppies typically reach their full adult size between 10-15 months of age. Breeds like Chihuahuas, Yorkshire Terriers, and Pomeranians will generally be fully grown at around 10-12 months old. Slightly larger small breed dogs like Miniature Pinchers, Shih Tzus, and Pugs will usually reach their full size closer to 14 or 15 months old.
Keep in mind that even after reaching their full height, small breed dogs may continue to fill out over the next couple months. While they are not getting any taller, their chests may broaden and they may become more muscular between 12-18 months old.
Small breeds that are fully grown at 10-12 months:
- Chihuahua
- Yorkshire Terrier
- Pomeranian
- Papillon
- Maltese
Small breeds that are fully grown at 12-15 months:
- Miniature Pinscher
- Shih Tzu
- Pug
- Boston Terrier
- French Bulldog
When are medium breed puppies fully grown?
Medium breed puppies are dogs that weigh between 25-50 lbs as adults. They usually reach their full adult size between 12-16 months of age. Some examples of medium breeds are Cocker Spaniels, Beagles, Border Collies, and Australian Shepherds. These dogs tend to be fully grown around 12-15 months old.
As with small breeds, medium breed puppies may continue to fill out past 16 months even though their height has stabilized. Their chests may widen and muscle mass may increase into maturity.
Medium breeds that are fully grown at 12-15 months:
- Cocker Spaniel
- Beagle
- Border Collie
- Australian Shepherd
- Dalmatian
When are large breed puppies fully grown?
Large breeds are dogs that weigh over 50 lbs as adults. This category includes popular breeds like Labrador Retrievers, Golden Retrievers, German Shepherds, and Rottweilers. These dogs normally reach their full adult size between 18-24 months old.
Large breeds grow rapidly during their first year, but their growth slows down significantly during their second year. Even after reaching their full height, large breed dogs will continue to fill out until they are 2 years old or so.
Large breeds that are fully grown at 18-24 months:
- Labrador Retriever
- Golden Retriever
- German Shepherd
- Boxer
- Rottweiler
When are giant breed puppies fully grown?
Giant breeds are very large dogs that weigh over 100 lbs as adults. Examples include Mastiffs, Great Danes, St. Bernards, and Great Pyrenees. These massive dogs can take up to 2 years to finish growing.
Giant breeds grow rapidly when young, putting on significant height in their first year. Their growth starts to slow around 18 months, but they will continue filling out and gaining muscle mass well into their second year.
Giant breeds that are fully grown at 18-24 months:
- Mastiff
- Great Dane
- St. Bernard
- Newfoundland
- Great Pyrenees
Other factors that influence growth
While breed size generally determines when a puppy will be fully grown, other factors can also impact growth rate and adult size. Here are a few other things that play a role in puppy development:
- Nutrition – Puppies fed a high-quality diet with proper levels of protein, fat, vitamins and minerals will grow and develop more optimally.
- Exercise – Regular, moderate exercise helps maintain lean muscle mass as puppies grow.
- Genetics – Some puppies are genetically predisposed to being smaller or larger than average for their breed.
- Gender – Males typically grow slightly bigger than females, especially in breeds with significant size differences between the sexes.
- Spay/neuter status – Altering a puppy too early can potentially limit how tall and heavy they grow.
Signs that a puppy is fully grown
Here are some signs that indicate your puppy has reached their maximum adult size:
- Growth plates have closed – These soft areas at the ends of bones harden when puppies are done growing.
- Reached typical size for their breed – Your pup is close to the average height and weight for their breed and sex.
- Slowing of growth – Your puppy’s growth curve starts to level off compared to when they were rapidly gaining height and weight.
- Fill out over height – Around a year old, your puppy puts on more muscle and fat than sheer height.
- Behavioral maturity – As your puppy becomes an adolescent their energy levels start to even out.
Tips for caring for growing puppies
Here are some tips for caring for your puppy as they grow and develop into adulthood:
- Feed a high-quality puppy food designed for their age, breed size, and activity level
- Keep exercise moderate and avoid too much high-impact activity
- Schedule regular veterinary checkups to monitor their growth and development
- Gently socialize your puppy to new people, animals, and experiences
- Use positive reinforcement training to begin instilling good behaviors
- Provide plenty of chew toys and interactive play to keep them entertained
- Be patient and consistent while your puppy masters housetraining
Frequently Asked Questions
At what age is a small breed puppy fully grown?
Most small breed puppies will be fully grown between 10-15 months of age. The smallest breeds like Chihuahuas reach their full size at around 10-12 months, while slightly larger small breeds like Boston Terriers or Pugs finish growing closer to 14-15 months.
At what age is a medium breed puppy fully grown?
Medium breed puppies typically reach their maximum size between 12-16 months of age. Popular medium-sized breeds like Cocker Spaniels, Border Collies, and Australian Shepherds are normally full grown by 12-15 months old.
At what age is a large breed puppy fully grown?
Large breeds are the slowest to finish growing, usually not reaching adult size until they are between 18-24 months old. Large dogs like Labradors, Golden Retrievers, and German Shepherds will generally be fully grown around 1.5-2 years old.
How can you tell when your puppy is fully grown?
Signs that a puppy has finished growing include reaching a height and weight typical for their breed, slowing of growth rates, filling out over getting taller, closure of growth plates, and increased behavioral maturity around adulthood.
Why does it take so long for big dogs to fully grow?
The incredible size that large and giant breed dogs reach takes longer to achieve because their bones, joints, and muscles need extra time to develop enough strength and coordination to support their massive adult bodies. Letting them grow slowly reduces risks of orthopedic problems.
Conclusion
Most puppies will be fully grown between 10-24 months of age, depending on their breed size. Small breeds finish growing first at 10-15 months, medium breeds at 12-16 months, large breeds at 18-24 months, and giant breeds at 24 months. Be patient during the long puppyhood of a big dog. With proper care and nutrition, they will eventually transform from cute, clumsy puppy to a beautiful, graceful adult dog.