If you're looking at that cute little furball and wondering just how big he's going to get, you're in good company.
Almost every puppy owner asks themselves this question - sometimes before they pick out their new pup, more often afterwards!
The thing is, no one can give you any guarantees about how tall your pup will be as an adult, or how much he will weigh.... but you do get some clues!
If you've brought home a purebred puppy then you've got a general idea of the breed's adult size.
After all a tiny baby Yorkie isn't going to end up the size of the neighbors Lab :)
But if Fido is a mixed breed puppy, then the element of 'surprise!' is going to be much greater.
Every single puppy is unique, and within the same breed (even within the same litter) there can be a noticeable difference in size between siblings.
Don't assume the pup who is the smallest at 6 or 8 weeks, is going to be the smallest as an adult.
The size of a very young puppy is not an accurate indicator of adult height/weight!
Genetics obviously play the biggest role in determining the adult size of any pup, but health and diet also have an effect.
Dogs come in a wider variety of sizes and appearances than any other animal on our planet!
Of course this huge difference in size (think Great Dane and Chihuahua!), means that there is no 'one-size-fits-all' calculation for estimating a puppy's adult weight.
But, there are some general guidelines that can help.
The most rapid puppy growth & development takes place between birth and 6 months of age.
But tiny and toy breeds develop at a faster rate and reach maturity much earlier than the large or giant breeds.
Period of most rapid growth in puppies...
Teacup and tiny breeds - Birth - 11 weeks
Small to medium breeds - Birth - 16 weeks
Large to Giant breeds - Birth - 5 months
The earlier, rapid growth usually starts to slow down considerably once your puppy reaches 65% of his adult height (between 4 and 6 months of age in medium to large breed pups).
In addition, studies done in the UK indicate that you can expect a small or medium breed puppy to reach 99% of it's adult weight somewhere between 9 and 10 months of age.
Large or giant breed puppies take longer to mature, and don't reach this stage until they're at least 12 - 18 months old.
Puppies from breeds at the top end of this scale (Great Danes, Mastiffs, Rottweilers etc.), are unlikely to really be 'finished growing' until they're 2 (or even 3) years old.
A pup reaches his full height before he reaches his full weight.
For example, at 4 months old most dogs will only have reached about 30% of their adult weight, but 60% of their adult height.
This variation puts their bodies 'out of whack' and is largely responsible for what I call the 'puppy uglies'... which is especially noticeable in large and giant breed pups.
I have one big-boy Rottweiler who looked like a 'bobble-head' for pretty much the whole of his second year of life!
He had a huge frame, massive head, and was on the top end of the height scale for a Rottie, but he was fairly 'slender'.... hence the bobble-head effect.
This pup actually didn't 'grow into' his bone structure until he was two and a half years old.
Now he weighs around 135lbs and is a big, muscular (lap) dog - not fat or overweight though thanks to his bone structure.
I've not seen quite such a slow puppy growth rate in any of my other Rottweilers, so this is a bit of an extreme example, but shows you what I mean.
There are lots of different methods of calculating puppy weight estimates, but none of them can predict exactly how much little Fido is going to weigh when he's all grown up.
However, they will give you a rough idea of how big your puppy is going to be.
Here are a few examples:
If you're the proud owner of a mixed-breed dog (or one who you were told was purebred, but you don't have papers and are beginning to have doubts about), there are some simple dog dna testing kits that you can buy online and use at home.
Then all you need to do is send off the sample (a simple cheek-swab with a Q-tip!) to the laboratory and wait for 2 - 3 weeks for the results.
You'll get info. on the dominant breeds in your dogs genetic make up and there are specific tests for mixed breeds, pure bred dogs and first-generation designer dogs (aka hybrids).
Although not guaranteed to be 100% accurate, these tests are a MUCH better way of determining your pup's eventual size, than pure guesswork.
Plus it can help you make you aware of a whole lot of other things that you can't see - including possible hereditary health conditions, dietary and exercise needs, breed-specific traits and instincts and much more.
It's very important to understand the relationship between proper nutrition and your puppy's growth.
Puppy weight estimates are based on a pup being well fed.
Obviously underfeeding will have a negative effect on your puppys' health and development, preventing him from reaching his full potential in terms of size/growth.
But many dog owners don't realize just how many problems overfeeding can cause.
Obesity in dogs is on the rise, and this is usually a direct result of feeding a dog too much in general or too much of the wrong food.
Just as with humans, obesity puts your dog at risk of all sorts of health problems, but overfeeding can also cause serious developmental issues particularly in large to giant breed pups.
Lifelong musculoskeletal (muscle, bone and
joint) problems can be caused by overfeeding your large breed puppy, by
feeding him the wrong type of food, or by adding unnecessary
The growth of a large breed puppy needs to be carefully controlled, and it's vital that you feed a puppy food that has been specifically formulated for large breed pups.
Lower levels of calcium, protein and calories are believed to help prevent 'too rapid' growth of his bones, and avoid the development of bone and joint disease.
If you have a large breed puppy, you don't want to miss reading my Interview with The Great Dane Lady who is an expert in the field of large breed nutrition.
Small breed puppies don't usually suffer from musculo-skeletal conditions the way large breed pups do, but they do have their own very individual needs when it comes to nutrition.
Tiny breeds have a fast metabolic rate and tiny tummies, and need a puppy food that contains higher levels of protein and fat, and to be fed more often.
Hypoglycemia (sudden, severe drop in blood sugar) can also occur in tiny breeds if they're not fed properly.
Sometimes owners can be impatient with the slow puppy growth rate of their large or giant breed pup, and want to 'speed up' his weight gain.
They just can't wait to get their pup to the 'big and brawny' stage!
But beware, this is absolutely the wrong thing to do and overfeeding may actually cause a puppy to never reach his full potential. Remember, patience is a virtue!
For an even better understanding of puppy weight estimates, take a look at the puppy growth chart for small/toy or large/giant breed puppies on my Puppy Weight Chart page.