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7 Effective Ways To Tell How Big Your Puppy Will Get


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Puppy owners are always curious about how big their puppy will get when they reach adulthood. This is a perfectly natural question, as everyone wants to make sure their new furry friend will be able to fit comfortably in their home.

However, a dog’s full-grown size is a complex trait to determine with 100% certainty. Adult body size can be affected by your puppy’s genetics, environment, sex, diet, and many other variables.

We’ll discuss a range of ways to help you estimate how big your puppy will get, from most effective to the least.

DNA testing is the most accurate predictor of adult dog size

In the past, the best way to predict a puppy’s adult size was to look at the size of their parents. However, this method is not always accurate, as puppies can inherit characteristics from grandparents, and their size can be influenced by other unforeseen variables.

In recent years, DNA testing has become a popular tool for estimating a puppy’s adult size. In dogs, the vast majority of genes that have been associated with body size have been scientifically validated. By looking at a puppy’s genetic code, experts can make more accurate predictions about how big a puppy will eventually become. In fact, Embark tests for five genes that together explain 85% of the variation in a dog’s adult body size.

DNA tests are not 100% predictive, but they are the most accurate way to estimate adult dog size when compared to external factors (parent’s size, breed, gender, etc.). As such, they have become an essential tool for breeders and pet owners who want to know what to expect from their dogs in the future.

Breed plays a big role

Another factor that can be helpful in predicting adult size is breed. If you’re certain of the breed of your puppy, you can estimate how big they will get.

For example, toy and miniature breeds typically weigh around 10–15 pounds as adults, and how much they differ from this range will usually only be by a couple of pounds in either direction. In contrast, large breeds can weigh over 100 pounds and have a much wider range of possible weights and sizes once fully grown.

Of course, there are always exceptions, but knowing the average size of a breed can give you a good idea of how big your puppy will be when they’re all grown up.

Curious about your dog’s breed mix? Find out with an Embark Breed ID or Breed + Health Kit.

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How big their parents are

Generally speaking, puppies inherit their size from their parents. If you know how big mom and dad are, you’ll have a good idea of how big your puppy will be.

This is a good place to start if you’re trying to estimate your puppy’s future size. However, this method has its limits, as puppies from the same litter can vary in size. You can also ask the breeder for an estimate of the parents’ sizes if you don’t know them yourself.

Keep in mind that your puppy may not reach their full adult size for several months (typically around one year of age for medium sized dogs or even later for giant breed dogs).

How much they eat when young

If your puppy is eating a lot and seems to be growing quickly, they are more likely to be a larger adult dog when compared to other dogs of the same breed. This isn’t to say it affects the overarching skeletal structure of the dog and that they will grow taller, for example. It pertains more to how much they will weigh as they get older which is another factor that contributes to their overall size.

On the other hand, if they seem to fill up easily and gain weight slowly, they’re more likely to be on the smaller side.

Ensuring your puppy isn’t being underfed is important, as this can actually stunt their growth and affect how big they get once they’re fully grown. Vice versa, if a dog is overfed when they’re a puppy, they can develop detrimental orthopedic conditions. It’s important to know how much to feed your puppy to avoid overfeeding or underfeeding them and the associated health complications that can come from this.

Overall, paying attention to their appetite can give you an idea of what to expect in terms of their adult size.

Sex has an impact

In general, male dogs tend to be larger than females. This difference is due to several factors, including hormones and skeletal structure. This applies to both mixed-breed and single-breed dogs. 

When looking at the general range of weights for your puppy’s breed, you can expect a male dog to be closer to the upper limit and a female to be closer to the lower limit. For example, if the general weight range for a breed is 30–45 pounds, a female dog would be closer to 30 pounds, while a male dog might be closer to 45 pounds.

The age when they’re spayed or neutered

There isn’t sufficient evidence to say with 100% certainty that spaying and neutering can affect how big a dog becomes. There are, however, recent studies that have found that dogs could end up being taller if they’re spayed or neutered before reaching full maturity (6–24 months, depending on the breed). 

The authors of the study found the reason these dogs end up being taller than dogs who’ve been neutered/spayed after maturity is because their bodies stop releasing hormones that normally halt growth. This ends up causing their legs to continue to grow beyond what would be considered normal or average. This means, depending on the age you get your puppy neutered or spayed, there’s a possibility the spay/neuter age will have an effect on how big they get when fully grown.

Paw size

Generally speaking, the larger the paws, the larger the dog will be. This is because paw size is directly related to leg length, and longer legs typically mean a larger overall frame.

Of course, this is not always accurate, as there are many small dogs with large paws and vice versa. However, it can help give you a general idea of your puppy’s adult size.

Alec Littlejohn Contributor

Alec Littlejohn grew up in a family of vets where pet care was discussed on a daily basis. He’s also a member of the Association of Professional Dog Trainers, a recognized author by the Dog Writers Association Of America, and now the lead editor at Pawscessories.

Read more about Alec Littlejohn

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