When Do Large Breed Puppies Stop Growing? What to Expect

If you just brought home a large breed puppy, you're probably already wondering how big this dog is actually going to get. Fair question. Especially when your "little" puppy is already taking up half the couch at four months old and showing zero signs of slowing down.

The short answer is that most large breed puppies stop growing between 12 and 18 months of age. But there's a lot more to it than just a number. Let's walk through what to expect as your large breed puppy grows, what affects their growth, and how you can support them along the way.

How long do large breed puppies grow?

If you're asking when do puppies stop growing large breed, the answer depends on whether your dog falls into the "large" or "giant" category.

Large breed dogs are breeds that reach 50 to 100 pounds as adults. They typically hit their full size between 12 and 18 months. Think Labrador Retrievers, Golden Retrievers, and German Shepherds.

Giant breed dogs are breeds over 100 pounds. Great Danes, Mastiffs, and Newfoundlands can keep growing until they're 18 to 24 months old. Yes, two full years of growing.

Here's something that catches a lot of owners off guard. Your puppy will probably reach their full height before their full weight. Most large breed puppies hit their adult height by around 12 months, but they keep filling out with muscle and body mass for several months after that. So even if your dog stops getting taller, don't let that fool you. They're not done yet.

For comparison, small breed puppies usually reach full size by 6 to 10 months, and medium breeds by 10 to 12 months. Large breeds simply need more time because their bones are bigger and take longer to develop.

Large breed puppy growth stages

Knowing what to expect at each stage makes it a lot easier to track your puppy's progress and spot any problems early.

Birth to 3 months

This is where your puppy's growth journey kicks off. Large breed puppies grow fast during this phase and will reach about 22% of their adult weight by 3 months. For a dog that will eventually weigh 80 pounds, that puts them around 17 to 18 pounds at this stage.

Most puppies go home with their new owners around 8 weeks, so you'll catch the tail end of this phase. You'll notice your puppy seems to grow overnight during these early weeks. Enjoy the small version while it lasts.

3 to 6 months

This is the fastest growth phase for large breed puppies. Your puppy will gain anywhere from 2 to 5 pounds per week, depending on the breed. By 6 months, they'll be at about 50% of their adult weight.

This is also when your puppy starts looking a little awkward. Their legs might seem too long for their body, and their paws will look comically oversized. That's totally normal. They're just growing into their frame. Think of it as the teenage years, but with more chewing.

6 to 12 months

Growth starts slowing down here, but it's still noticeable. By 12 months, your large breed puppy will be at roughly 83% of their adult weight. They'll probably be close to their full height at this point too.

This is also the adolescent phase, so expect some behavioral changes on top of the physical ones. Your puppy might push boundaries and seem to forget everything you've taught them. Stick with it. This phase passes. We promise.

12 to 18+ months

This is the home stretch. Most large breed puppies reach their full adult size somewhere in this window. They're not getting taller anymore, but they're filling out with muscle and reaching their final weight.

Giant breeds may keep filling out until they're 24 months old. Some very large breeds, like Mastiffs, might not look fully mature until they're close to 3 years old. Patience is part of the deal with big dogs.

What are growth plates and why do they matter?

Growth plates are soft areas of cartilage near the ends of your puppy's long bones. They're what allow your puppy's bones to grow, and they're also the reason you need to be careful about exercise during puppyhood.

As your puppy grows, these plates slowly harden and calcify. Once they're fully hardened, they "close," and the bone has reached its final length. At that point, your puppy is officially done growing.

In large breed dogs, growth plates typically close between 14 and 20 months of age. That's a lot later than small breeds, whose growth plates may close as early as 6 to 8 months.

Why does this matter? Growth plates are softer and more fragile than mature bone. Too much high-impact exercise before they close can lead to uneven bone growth, joint problems, or lasting pain. It's one of those things that's easy to prevent but hard to fix later.

Factors that affect how fast your large breed puppy grows

Not every large breed puppy grows at the same pace. Here are the main factors that influence how quickly your puppy reaches their adult size.

Genetics and breed

This is the biggest one. Your puppy's breed sets the general growth timeline and adult size. A Labrador Retriever follows a different growth pattern than a Great Dane, even though both are large or giant breeds.

Mixed breed dogs can be harder to predict. If you adopted a mixed breed puppy and aren't sure how big they'll get, your vet can help estimate their adult size based on their current weight and paw size. It's not an exact science, but it gives you a ballpark.

Nutrition

What you feed your large breed puppy directly affects how they grow. Large breed puppies need food that's made for their size. These formulas control the rate of growth, which is key for preventing joint and bone problems.

Here's something a lot of people don't realize: growing too fast is actually a bigger concern than growing too slowly for large breeds. Rapid growth puts extra stress on developing bones and joints, which can lead to conditions like hip dysplasia. Don't add calcium or mineral supplements unless your vet tells you to. More isn't always better.

Spaying and neutering timing

This is worth talking to your vet about. Studies show that early spaying or neutering, before 6 months, can delay growth plate closure in large breed dogs. That means the bones keep growing longer than they normally would, which can change your dog's proportions and raise the risk of joint problems.

A lot of vets now suggest waiting until large breed dogs are at least 12 to 18 months old before spaying or neutering. For some giant breeds, waiting until 24 months may be the better call. Your vet can help you decide the right timing for your dog.

Health conditions

Parasites, chronic illness, and other health issues can slow your puppy's growth. Regular vet checkups help catch these problems early so they don't get in the way of your puppy's development.

Intestinal parasites are especially common in puppies and can really hold back growth if they're not treated. Make sure your puppy is on a deworming schedule that your vet recommends.

How to support healthy growth in your large breed puppy

You can't change your puppy's genetics, but you can give them the best shot at healthy growth.

Feed the right food

Pick a puppy food that's specifically labeled for large breed puppies. These formulas have the right balance of calcium, phosphorus, and calories to keep growth steady and controlled.

Follow the feeding guidelines on the bag, but also check in with your vet to adjust portions for your puppy's specific needs. A good rule of thumb: you should be able to feel your puppy's ribs without pressing hard, but you shouldn't be able to see them.

Exercise the right amount

A good rule of thumb is 5 minutes of exercise per month of age, up to twice a day. So a 4-month-old puppy should get about 20 minutes of exercise at a time.

Until your puppy's growth plates close, skip the high-impact stuff like long runs, jumping from heights, and lots of stair climbing. Stick to gentle walks on soft surfaces like grass, and let your puppy set the pace during play.

That doesn't mean your puppy should sit around all day. Free play in the yard, short walks, and gentle socializing are all great for large breed puppies. Just stay away from forced, repetitive, or high-impact exercise. There will be plenty of time for long hikes once they're fully grown.

Keep up with vet visits

Regular vet visits let you track your puppy's growth and make sure everything looks good. Your vet can tell you if your puppy is growing at a healthy rate and flag any concerns before they become bigger issues.

Most puppies need several vet visits in their first year for vaccines and checkups. After that, yearly visits are usually enough for healthy dogs.

Signs your large breed puppy has stopped growing

Wondering if your large breed puppy is finally done growing? Here are some signs to watch for.

Their paws look proportional to their body. Remember those oversized puppy paws? When they no longer look too big for your dog, growth is probably winding down.

Their weight holds steady. If you're tracking your puppy's weight and it stays the same from week to week, they've likely hit their adult weight.

They're getting broader, not taller. If your dog is putting on muscle but not gaining height, they're in the final stage of growth.

Your vet says their growth plates have closed. This is the surest sign. Your vet can take X-rays to confirm whether the growth plates have fully hardened. If you want a definitive answer, that's the way to get one.

Large breed puppy growth FAQ

When do Labs stop growing?

Labrador Retrievers typically reach their full height by 12 months and their full weight by 12 to 18 months. Most Labs weigh between 55 and 80 pounds as adults, with males on the larger end.

When do German Shepherds stop growing?

German Shepherds usually hit their adult height by 12 months but keep filling out until about 18 months. Some won't reach their full muscular build until they're 2 years old. Adult German Shepherds typically weigh between 50 and 90 pounds.

When do Golden Retrievers stop growing?

Golden Retrievers follow a timeline similar to Labs. They reach full height around 12 months and full weight by 14 to 18 months. Adults usually weigh between 55 and 75 pounds.

How do I know if my large breed puppy is underweight or overweight?

Try the rib test. You should be able to feel your puppy's ribs with light pressure, but you shouldn't see them. If the ribs are visible, your puppy might be underweight. If you can't feel them at all, they might be carrying too much weight. Your vet can also do a body condition score to give you a clearer picture.

Should I use a puppy growth chart?

Growth charts are a helpful starting point, but they're general guidelines. Every puppy is different, and things like genetics, nutrition, and health all play a part. Use a chart as a reference, but work with your vet to keep tabs on your individual puppy's progress.