How Big Will My Puppy Get?

Whether we are shopping for a pet door, a dog bed, or just wondering, we have lots of questions about our dog's size. How big will my furry friend get as they become fully grown? When do puppies stop growing? How big will my adult dog get? Are puppy weight calculators even accurate?

These questions aren't easily answered by a quick Google search, especially if you have a mixed breed puppy (you typically know what you're going to get with a purebred puppy). Measurements like your puppy's weight and paw size can help you predict their adult-size. However, dog breeds are not all made equal-- small breeds, medium breeds, large breeds, and giant breeds all mature at different paces. 

Mikey puppy pics - when do dogs stop growing - dog weight calculator

There's a lot of variation that can impact how big your little puppy with get. While predicting a puppy's adult weight and height is not an exact science, there are a few ways to predict future growth and estimated full size with reasonable confidence.

How to Tell How Big Your Puppy Will Get

Predicting the size of your puppy requires a few basic steps:

    1. Weigh your new puppy
    2. Once you have established their current weight, go to
    3. Select your puppy's breed from the list of dog breeds (approximate is ok)
    4. Select your dog’s birthday to reflect weeks of age or months of age (approximate is ok)
    5. Enter the date and weight from the last time you weighed your dog
    6. See the puppy weight chart and projected adult size

The free website is a neat way to predict your puppy's adult weight by comparing their current size with historical data of other dogs from the same breed. This means that dogs from larger breeds will be ranked against their own breed while small dogs like terriers will be ranked against other terriers.

While the tool isn't an exact indication of what your puppy's adult size will be, it's a fun way to at least get in the ballpark! Factors such as differing height and weight gain are not reflected in the weight calculator (or adult height), so it's important to keep in mind that it's not a comprehensive indication of your dog's specific growth rate, and could change for naturally larger dogs.

Let's put the puppy growth calculator to the test! As curious pet parents, we've weighed our border collie puppy Mikey frequently since getting her in July so we can look into how quickly PuppyChart’s projection stabilizes.

Mikey's Growth Results

When we first took Mikey home, she was only an 8.2lb ball of fluff and cuteness. At that number of weeks (57 days), PuppyChart predicted she would be only 29.3 lbs at maturity, which is a bit on the smaller end for her pooch breed. Remarkably, even though we weighed Mikey 26 more times her PuppyChart projection remained largely consistent, fluctuating between 28.9 and 33.6 lbs and usually in the 31-32 range as shown in red in the graph below.

Mikey’s still only a little over 5 months and still has some more growing to do, but so far it really looks like she’s headed to become about 32 lbs. The PuppyChart projection means that even at only 8 weeks, you can get a pretty good idea of how big your dog will grow. What a great way to see how big my dog would get. Now I know what size of dog door, bed, and crate to get for Mikey!

Mikey's Actual and projected weight growth from puppy weight calculator

How Much Will My Dog Weigh If They’re a Mutt?

Well, that’s a bit harder. You could probably average the puppy growth chart projections based on each breed component to get an idea. Another fun thing you could do with rescues is to work backward to figure your dog’s actual birthday. If you rescued a dog that was only 20 lbs and later grew to be 65 lbs, you can work backward to extrapolate that your puppy was about 11 weeks when you got her!

Dog weight calculator - how big will my dog get and when do dogs stop growing? Looking for an alternative weight calculator? The American Kennel Club has a breed weight chart for a huge list of small dogs and large dogs (from Chihuahuas and Beagles to Mastiffs and Great Danes). This chart is a nice quick way to see just how big dogs can get!

Did you do this test or another method? What do you think is the best dog-size calculator? Tell us your thoughts!

Predicting your puppy's size as an adult isn't just for fun, but can be necessary when buying things like dog beds, dog food, or pet doors. has dozens of brands of pet doors for every breed and every installation type. 

Nick Pullano

Written by

Nick Pullano


Pets: I have a half border collie, half angel named Mikey.
Fun stuff: My dog's tongue is slightly longer than her face, so frequently her tongue sticks out a little even when her mouth is closed.


Pets: I have a half border collie, half angel named Mikey.
Fun stuff: My dog's tongue is slightly longer than her face, so frequently her tongue sticks out a little even when her mouth is closed.

Leave a Comment

Please note, comments must be approved before they are published