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How Fast Do Puppies Grow? Puppy Growth Stages

Veterinary reviewed by Dr. Linda Simon.

Bringing home a new puppy is an incredibly exciting moment!

As a new puppy owner, you expect that your puppy will grow both physically and mentally during their time with you. 

However, you may have questions including: How fast will my puppy grow?

Puppies grow about 5-10% per day from the age of 1 week to 8 weeks. From then on, the growth rate will slow down but they do grow for another 6 to 18 months.

The absolute amount varies due to the varying birth weights of small to giant breeds.

Other questions you might have which will be covered below: When will my puppy stop growing? How can I tell how big my mixed breed puppy will be?

Puppy Growth Stages

Prior to birth, puppies are developing in the mother dog during the pregnancy for about 63 days.

The first several weeks after a puppy is born involve even more growth and development. These important first weeks and months can be broken down into several different puppy growth stages. 

1. The Neonatal Period (birth-2 weeks)

In the first week of a puppy’s life, they cannot see or hear and spend most of their time snuggling with their mother and siblings, eating and growing quickly.

In this first stage of puppy growth, a puppy may double their weight. 

Puppies are also able to vocalize during the neonatal period and can crawl, but cannot walk.

2. The Transitional Period (2-3 weeks)

The next several weeks involve a puppy’s eyes and ears opening, adding new senses to their world. Puppies will also start to get their puppy teeth in week 3 or 4 of their life. 

During the transitional period of growth in puppies, your puppy will also learn how to play fight with siblings and even how to wag their tail!

3. The Socialization Period (3-12 weeks)

By 8 weeks old, your puppy has started to develop fear responses as well as their own individual personality.

This period of growth is one of the most important times of your puppy’s life, as the experiences that they have during their socialization period will shape their confidence and fears for the rest of their life.

Not only is your puppy going through a behavior growth stage at this time, but they are also learning how to walk and bark.

Their puppy teeth will come in more completely – all 28 of them!

Puppies will also start to develop control of their bowel and bladder movements. Exceptional breeders may even start potty training litters as soon as 5-6 weeks old.

4. The Juvenile Period (12 weeks-adolescence)

At this point, your puppy has fully developed their senses and their growth rate is slowing down, although your puppy will continue to grow for at least several months. 

From 4-6 months, your puppy will be teething again, although this time the 28 puppy teeth will be replaced by 42 adult teeth.

Mixed breed puppy in a puppy sit position. Big paws indicate growth spurt.

Your puppy still needs careful attention and thoughtful exercise to keep their joints safe, as their growth plates are still open. 

5. Adolescence (varies)

Adolescence starts anywhere from 5-18 months and can continue until your puppy is 2-3 years old in some breeds.

Your puppy’s size and breed will play a role in determining how long they go through their adolescence period before moving on to adulthood. 

In general, the smaller the dog, the faster they will reach adulthood. Larger dogs start adolescence later in life and often have longer periods of adolescence.

How Fast Do Puppies Grow?

Newborn puppies will double their birth weight within their first week of life. After they are 1 week old, puppies will gain an average of 5-10% a day until about 6 to 8 weeks of age. 

Even though puppies are gaining a similar amount of weight, they will vary in size by 6 weeks due to their birth sizes and breeds.

A small breed may only gain 5 ounces a week but a large dog might gain over 2 pounds in the same timeframe!

When Do Puppies Grow the Most?

Puppies grow the most in their first week of life, doubling in size from their birth weight.

They will continue to rapidly grow until 6-8 weeks of age.

After that point, puppies will grow for at least several more months (sometimes even a year or two) although the growth rate will be slower.

The majority of dogs will continue to slowly grow with age.

However, some breeds of dogs may have a second growth spurt around 6 months of age, especially if they are a larger breed.

When Do Puppies Stop Growing?

Growth continues to happen until 6-24 months for most dogs, depending on the breed and size.

While this growth is continuing, even leading to doubling in size again, it’s more spread out than the rapid growth that happens when they are first born.

The size of your dog is the biggest factor in determining when they will stop growing.

Toy dogs are considered the smallest breeds. These breeds will likely reach their full size by 6-8 months and be fully mature by a year old. 

  • Papillon
  • Toy Poodle

Small dog breeds will usually reach their full size by 8-10 months old.

Medium-sized Breeds will finish growing in height by around 12-14 months, although they will not be done filling out to their final weight until 18-24 months.

  • Border Collies
  • Basset Hounds
  • Husky

Large breeds of dogs take slightly longer than medium dogs to finish growing.

An average large dog will be fully grown around 14-18 months, although they can have a second growth spurt between 8-14 months that speeds up their growth later in life than smaller dogs.

As with medium breeds, it may take 18-24 months for a large dog to reach their final weight.

  • Rottweiler
  • German Shepherd
  • Boxer

Giant breeds are the largest among dogs. It’s unlikely that a giant breed would reach their final height until around 18 months of age.

Giant breeds also tend to continue to grow until they are 2-3 years by gaining weight and filling out their large, gangly, adolescent bodies.  

  • Great Dane
  • Irish Wolfhound

Puppy Joints

Dogs finish growing when their growth plates close. Growth plates are a soft area of cartilage from which bones (such as your puppy’s legs) grow and extend.

Once fully grown, the growth plates will close and become hard bone, and the location (which can be seen on x-rays) is known as the epiphyseal line. 

Hormonal changes through adolescence trigger the growth plates to begin closing, which is partly why the timing can vary so much for different breeds.

If you are unsure if your puppy’s growth plates have closed, it’s best to wait a little longer before adding harder exercises or jumping into their life.

The majority of breeds will have their growth plates close by 18 months, sooner for smaller dogs. 

Knowing an estimate of when your puppy’s growth plates close is important because too much exercise or stress on their joints before they finish growing can cause injuries.

If your dog’s already experiencing slight limping due to inappropriate for your puppy’s joints, check out what to do about puppy limping.

When Do Labs Stop Growing?

As a medium to large breed of dog, Labrador Retrievers will often stop growing taller by 12 months of age.

However, Labrador Retrievers may continue to fill out and gain weight for another year after they have stopped growing in height. 

Since Labrador Retrievers are a breed known for easily being overweight, it’s important to watch your puppy to make sure they don’t become obese.

Not only is obesity bad for their health, but it also means that your puppy won’t be able to participate in as many activities with you. Make sure you provide the right exercise for your puppy.

If you know the parents of your Labrador Retriever, you can get a better idea of how big your dog might be when your lab is fully grown.

Genetics come in handy, huh?

Labs that are smaller will finish growing faster than some of the larger versions of the breed.

While some breeds don’t have many differences in size, Labrador Retrievers can have a wide range of adult sizes depending on if your Lab puppy came from show or working lines.

The average Labrador Retriever weighs 50 pounds at 6 months old but may weigh as little as 30 pounds or as much as 60 pounds depending on the individual puppy.

If you have any concerns about your puppy’s weight and growth, make sure to check with your veterinarian to ensure they are growing healthy and strong.

How to Tell How Big a Mixed Puppy Will Get

If you don’t know your puppy’s parents, or they are different sizes, it can be difficult to determine how big your mixed breed puppy will get.

Fortunately, there are a few formulas that can help give you an idea of how much your puppy will grow. 

For dogs that are expected to be a toy or small size as an adult, the best time to estimate their adult weight is when the puppy is 6 weeks old.

The easiest estimate for these smaller breeds is to multiply how much they weigh at 6 weeks old by 4

As an example, if your small breed dog weighs 3 pounds at 6 weeks old, you can estimate that they will be 12 pounds as an adult (3 x 4). 

Larger breeds sometimes require a bit more effort to calculate how big the mixed breed puppy will get.

If your puppy is likely a medium or large mixed breed dog, you’ll want to start with their weight when they are 14 weeks old. 

Calculating the estimated size of a medium to large mixed breed dog involves taking the weight at 14 weeks old, and then multiplying by 2.5 to get the final number.

As an example, if your 14-week-old puppy weighs 25 pounds, then take 25 times 2.5 to get 62.5 pounds as an estimate for your puppy’s adult weight. 

What happens if you don’t know how much your puppy weighed at 14 weeks old?

If that’s the case, you can also estimate their adult weight when they are 6 months old.

Medium and large breed dogs weigh about two-thirds of their adult weight at 6 months, and giant dogs weigh about half of their adult weight at 6 months. 

If you have vet records with weights from when your dog was a puppy, did this formula work for your dog? Let me know in the comments!

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Disclaimer: This blog post does not substitute veterinary attention and does not intend to do so. I am not a veterinarian or pet nutritionist. If your dog shows any sign of illness, call your vet.

About Danielle

Equipped with 5+ years of expertise as a Rottweiler owner, I partner with licensed veterinarians and trainers to share research-backed and actionable advice for you and your furry friend.


Monday 2nd of August 2021

Thank you for sharing. beneficial information