Whenever you bring a new puppy home, at some point, you will begin to wonder, “how big will my puppy get?” Judging how big your dog will get is not an exact science, and it’s made even more complicated if you’re trying to tell how big a mixed breed puppy will get. Nevertheless, a puppy weight calculator can put you in the right ballpark.
Knowing how big your dog will get can also help prepare you for the future regarding how much exercise or space your dog needs, what size crate or harness to buy.
So How Can I Estimate My Dog’s Adult Size?
If you bought a purebred puppy and were able to see both parents, guessing your puppy’s adult size is easy. The most likely answer is that your puppy will fit somewhere between mom and dad or simply within the normal range for the breed standard.
But if you bought or adopted a mixed breed puppy, things get trickier.
Firstly, the rate at which puppies reach full size depends on your category your dog falls into.
There are five in total, and each reaches maturity at a different age. It is also essential to have an idea about when your puppy will stop growing.
Dog Size Categories
| Category | Adult Weight | Age They Stop Growing | Breed Examples |
| Toy | Up to 12 pounds | 8 to 9 months | Chihuahua, Yorkshire Terrier, Pomeranian |
| Small | 12-25 pounds | 8 to 12 months | Beagle, Dachshund, Pug |
| Medium | 25-50 pounds | 9-12 months | Cocker Spaniel, Whippet, Basset |
| Large | 50-100 pounds | 12-18 Months | German Shepherds, Labradors, Boxers |
| Giant | Over 100 pounds | 12-18 Months, but can take up to 2 -3 years to reach full weight. | Great Dane, Irish Wolfhound, Newfoundland |
Suppose you know where the parents of your mixed breed puppy fit on this scale. In that case, you can jump to the puppy growth calculator below to get an estimation of your puppy’s adult size.
However, you may be entirely in the dark about who your dog’s parents are or exactly how old your puppy is, which can make calculating the adult age a little more complicated.
Therefore, let’s look at all the factors involved.
How Do I Know if I Have a Small, Medium, or Large Mixed Breed Puppy?
Judging which category your dog is in should be easy if you know who the parents are. For instance, if you have a Dalmadoodle, a mix between a Dalmation and Poodle, both parents are medium to large breed dogs, and so your pup will fit in the same range.
Similarly, if you own a Minchi, both parents are toys, and so your dog will likely stay very small.
If the parents vary significantly in size, your pup is more likely to stay close to the mother, with females usually closer to the mother’s height and males slightly bigger. Unless the dad was smaller, in which case the puppies should mostly be smaller than the mom.
If you have no idea who the parents are, you can use your pup’s age and weight at the moment to assess in which size category it will fall.
Owners of rescues or adopted puppies may not be sure how old their puppy is. If this is the case, the best way to tell your dog’s age by looking at the teeth.
A puppy’s baby milk teeth emerge between 3 and 6 weeks, and their adult teeth will start to come in between 12 and 16 weeks. Usually, they begin to lose their front row teeth just as they turn three months old, which is a useful marker.
From 16 weeks, they start to lose their back teeth, and this continues until they are about 6 months old.
| Age | Toy dog weight in ounces | Small dog weight in pounds | Medium dog weight in pounds | Large dog weight in pounds | Giant dog weight in pounds |
| 8 weeks | 11 – 39 oz | 1.5 – 4 lbs | 4 – 8 lbs | 9 -15 lbs | 16 – 21 lbs |
| 9 weeks | 12 – 42 oz | 1.7 – 4.5 lbs | 4.5 – 9 lbs | 10 -17 lbs | 18 – 23.6 lbs |
| 10 weeks | 13 – 45 oz | 1.9 – 5 lbs | 5- 10 lbs | 11.3 – 18.8 lbs | 20 – 26.3 lbs |
| 11 weeks | 14- 49 oz | 2.1 – 5.5 lbs | 5.5 – 11 lbs | 12.4 – 20.6 lbs | 22 – 28.9 lbs |
| 12 weeks | 15 – 53 oz | 2.3 – 6 lbs | 6 – 12 lbs | 13.5 – 22.5 lbs | 24 – 31.5 lbs |
| 13 weeks | 16 – 57 oz | 2.5 – 6.5 lbs | 6.5 – 13 lbs | 14.6 – 24.4 lbs | 26 – 34.1 lbs |
| 14 weeks | 17 – 60 oz | 2.7 – 7 lbs | 7 – 14 lbs | 15.8 – 26.3 lbs | 28 – 36.8 lbs |
| 15 weeks | 19 – 65 oz | 2.9 – 7.5 lbs | 7.5 – 15 lbs | 16.9 – 28.1 lbs | 30 – 39.4 lbs |
| 16 weeks | 20 – 70 oz | 3.1 – 8 lbs | 8 – 16 lbs | 18 – 30 lbs | 32 – 42 lbs |
Make Use of the Puppy Weight and Height Calculator
Using the charts above to check which weight range your puppy is growing in will give you a rough idea of your puppy’s adult size and when it will stop growing.
But what if you want a more specific estimate of your puppy’s adult weight and height?
If this is the case, then we can make use of a few calculations to get a better idea using the size categories:
Weight Calculator 1
Small and Toy Breeds
For small and toy breeds, the calculation is straightforward.
Take your puppy’s weight at six weeks and double it, then double it again.
For example, if your puppy weighs 2 pounds at six weeks old, it should end up about 16 pounds as an adult since 2 x 2 = 8 and 8 X 2 =16.
Medium and Large Breeds
With medium and large breed puppies, you take their weight at fourteen weeks. Double their weight at fourteen weeks and then add half of their fourteen-week weight to the total.
Therefore, if your medium to large breed puppy weighs 15 pounds, you double that to 30 and add 7.5 (half the original weight). So your dog should end up weighing around 37.5 pounds.
In short, the calculation is 2.5 times the weight at fourteen weeks.
Giant Breeds
Giant breeds typically are double the weight they are as adults than they were at around 22 weeks. Therefore, take the weight at 22 weeks and multiply it by two.
Weight Calculator Method 2
This method depends on having a good idea when your dog will stop growing. It relies on the idea of adding up how much your puppy grows every week.
For this, you will take your puppy’s weight and divide it by the age in weeks. You then times it by the number of weeks in a year (52).
So if your puppy weighs 15 pounds at 14 weeks, it would be:
15/14 = 1.07 x 52 = 55.7 pounds
This method relies on your puppy finishing growing at 12 months.
Therefore, if you have a small breed that will likely stop growing at eight months, change it to multiplying by 32 weeks instead of 52. On the other hand, if you have a large or giant breed, multiplying by 72 weeks may be more accurate.
Height Calculator
A general rule of thumb for a dog’s height is that they have usually reached around 75% of their adult height at 6 months. This means that to work out their adult height, you can take their height—measured from the top of their shoulders, not their head— multiply it by a hundred and divide by 75.
How Accurate is My Puppy’s Weight and Health Calculator?
It’s important to know that any calculation done online or even by a professional is only ever a rough estimate. They are rarely 100% accurate. Instead, they should preferably be used as a loose guideline for what you prepare for when your dog is an adult.
Puppies also do not always grow consistently, often popping up in leaps and bouts, making exact estimates hard.
There are several other ways to help you make sure you get closer to the mark.
Taking your puppy to the vet can help make use of the vet’s expertise to guess your mixed breed’s ancestry. A vet also has the experience of watching hundreds of growth curves on different dogs, so they can give you a good idea of what to expect.
This is especially helpful if the puppy’s adult coat has not yet come in, as the adult coat can indicate what may lay in your mixed breed’s ancestry.
Some markings may still be a tip-off, though.
For example, medium-sized puppies with black coats and white paws or white markings on their chest often have some border collie in their background. Likewise, black face masks on a dog might hint at either mastiff or German Shepherd ancestry. At the same time, blue eyes are often signs of a Husky.
Another avenue to explore is to have your dog’s DNA tested. This can give your puppy’s exact genetic age and a look at all the dogs in her ancestry, which will help give you an idea of how big she will be if she is a mixed breed.
Aside from genetics, there are also other factors to consider when calculating your dog’s adult size.
Other Factors that Influence Puppy Growth and Size
Consider Your Puppy’s Diet
Both over and under-nutrition can affect a dog’s growth. Malnutrition can stunt a puppy’s growth and cause health issues.
Similarly, diets too high in calories, fats, and calcium can cause a dog to grow faster, usually at the expense of their health.
This is particularly dangerous for large and giant breed dogs. Overfeeding through too many calories or high fats can cause obesity. A maximal growth rate can cause lifelong musculoskeletal disorders.
Too much calcium also causes bone deformities, so never feed your puppy a calcium supplement unless the veterinarian specifically recommends it.
Consider Paw Size and Bone Structure
Conventional wisdom has everybody agreeing that giant paws equal a giant dog, and this is partially true. A puppy whose legs and paws look too big for it will generally grow quite big.
But this isn’t always the case. Sometimes puppy body parts grow at different rates, and sometimes their paws and legs simply go through a spurt that the rest of their body hasn’t yet caught up to. Awkward proportions are often more a sign of juvenile development than adult size.
Another point to keep in mind is that various breeds have very different bone structures. A Greyhound or a Borzoi might grow as tall as 30 inches high at the shoulders but have a very fine bone structure and lack the giant paws of a Great Dane or English Mastiff.
On the other hand, a Basset or a Bulldog might have giant paws and a much larger bone structure, even they only reach fifteen inches high.
Worms
Another health concern affecting a puppy’s growth rate that slow it down is a hookworm or roundworm infection. Luckily, in most cases, a simple deworming should put your dog back on track.
Loose Skin
In general, a lot of loose skin on a puppy is a good sign that there is plenty of room for it to grow. However, like the paws, loose skin can also be breed-specific, with Shar-Peis, Pugs, Bassets, and others keeping the loose skin throughout their lives.
Spaying/Neutering
In some cases, studies show that neutering a dog before seven months old reduces testosterone and delays the closing of the puppy’s growth plates. While this may cause the dog to grow slightly taller, it also increases the risk of joint issues.
Gender
Provided you know in what size category your puppy falls, it should be remembered that females are almost always smaller than males. So if you have a female Saint Bermastiff, it will likely fall on the smaller end of the scale.
The Parents
Although we discussed parents above, another point to note is that if you have a mixed breed, the progeny cannot fall outside the parameters of the two parent breeds. This means that if you have a German Shepherd Corgi cross, the puppy cannot be bigger than a German Shepherd or smaller than a Corgi.
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Figuring out exactly what size your puppy will grow up to be can be a bit of a headache. So, we hope we’ve put together enough information for you to put you in the ballpark. Being ready for your adult dog can help you prepare for its exercise and space needs, as well as equipment such as a crate or harness.
Meet Your Experts
Author
Tamsin de la Harpe has nearly two decades of experience with dogs in rescue, training, and behavior modification with fearful and aggressive dogs. She has worked closely with veterinarians and various kennels, building up extensive medical knowledge and an understanding of canine health and physiology. She also spent two years in the animal sciences as a canine nutrition researcher, focusing on longevity and holistic healthcare for our four-legged companions. Tamsin currently keeps a busy homestead with an assortment of rescue dogs and three Bullmastiffs.