How Big Will My Puppy Get? – Puppy Weight Calculator

Featured image by © / dvigalet

How Big Will My Puppy Be?

So, you just got a cute little puppy that just doesn’t seem to stop growing any time soon. Indeed, your cute little ball of fur won’t stay small for long. “How big will my puppy get?” is one of the questions most asked by new pet owners.

Guesstimating a Puppy’s Adult Size

Some people will guesstimate an adult dog’s size based on the size of the puppy’s paws, however, the best way is to use a puppy weight calculator. The answer to this question will determine your future plans for your pup. Do you have a large enough crate? Is your house and yard adequate?

How big will my puppy be as an adult
Cavachon puppy in basket. How big will it get? © / JStaley401

When Will My Puppy Stop Growing?

Although it may seem like your pup will keep growing forever, he will reach adult size before you know it. The larger the dog breed, the more months they take to grow to adulthood. On the small end of the scale, your pocket-sized breeds typically reach adult size in 6 – 12 months, at a 5oz gain per week, whereas the giant sized breeds can grow for 18 – 24 months, at a 2lb gain per week.

Factors That Determine Size

How big are their parents? 

Hopefully you got to see how large the parents were. However, this is not always possible, especially with rescue dogs.


Breed Type  

Consider whether your pup is a toy, small, medium, large, or giant breed, and how long they take to reach adult size. There is less guesswork when you’re dealing with a purebred puppy, but mixed breeds can be more challenging. it’s best to use a puppy weight calculator in this scenario.


Litter size 

Smaller puppies usually tend to come from larger litters. The number of siblings your puppy had can influence how big your puppy will grow.


Male or Female   

Generally speaking, female dogs are smaller than males.



Nutrition is one of the most important factors in how big your puppy will grow. Mom’s milk is essential for those first few weeks. After adoption, ensure you give your puppy quality food to meet their nutritional needs for each stage of their life.



Early neutering can impact the size of your dog. Neutering removes hormones that tell bones when to stop growing. As a result, early neuters have a tendency to be taller.

Puppy Weight Calculator

Calculate Your Puppy’s Adult Weight

There are several ways to predict your puppy’s adult size. We like to use the following method, especially with rescue dogs, as we may not always know the details and lineage. Ideally this formula should be used at certain times according to size:

  • Small breeds should be weighed in at 12 weeks old
  • Medium breeds should be weighed in at 16 weeks old
  • Large breeds should be weighed in at 20 weeks old

Apply the following formula:  Adult Weight = ( Weight (lbs) / Age (weeks)  ) * 52

 So lets say you adopted a cute little mutt, like we did, and she weighed in at 6 lbs at 12 weeks. You could expect her to be 6/12 * 52 = 26lbs as an adult.

The formula is a good approximator for what to expect so you can plan accordingly, but mother nature can always surprise you.

Puppy Weight Calculator
Age (Weeks) Weight (lbs) Projected Weight (lbs)