How Big Will My Puppy Get? Different Ways To Estimate Adult Size

• Not a substitute for professional veterinary help.

No adventure compares to the thrill of bringing home a new puppy. As your pal grows, one question looms large: “How big will my puppy get?”

Your puppy’s growth rate affects more than their ability to fit on your lap. Knowing your puppy’s potential adult size helps you plan their diet, exercise routine, and living arrangements. While there’s no magic formula to predict the final weight with absolute certainty, there are some helpful guidelines to get a rough estimate.

In this article, we’ll hear from the experts on estimating your pup’s future size. We’ll also share tips for monitoring their growth to ensure they stay healthy and on track.

Average Size By Breed

If you know your dog’s breed, predicting their adult size becomes much easier. According to Dr. Wayne M. Johnson, a veterinarian at Birdneck Animal Hospital, you can determine a purebred dog’s size based on breed standards and parent size.

One reliable way to predict how big your puppy will be is by referencing breed standards established by organizations like the American Kennel Club (AKC), which outline expected height and weight ranges for purebred dogs.

For mixed breeds, identifying the parent breeds can provide valuable clues about potential size. If your puppy’s family history is unknown, consider a DNA test.

It’s important to remember, however, that individual growth can vary. While many breeds have standard weight ranges, genetics can significantly affect your dog’s final size. For instance, if both parents are smaller than average for their breed, your pup is also likely to be smaller.

To help you calculate how big your puppy will get by breed, take a look at the five size categories. These estimates can help you determine your puppy’s potential weight and height.

Formula for Estimating Adult Size

While there’s no official formula to predict a puppy’s adult weight, experts have devised some handy methods to get a rough estimate.

Dr. Johnson shares a simple technique. “It’s not perfect, but it’s a good ballpark estimate,” he admits.

• For small breeds: triple the puppy’s weight at 8 weeks
• For medium and large breeds: double the puppy’s weight at 16 weeks

You’ll also find many puppy size calculators online—these may consider factors like breed, sex, current weight, and age for a more tailored estimate.

Calculators and formulas are convenient and a good starting point for determining how big your puppy will get. But they can’t always make accurate predictions since they don’t know your pup personally and can’t account for any unique genetic variations.

“These calculators are meant as a ‘guesstimate’ to be combined with body condition scores and physical exam findings,” explains Dr. Nell Ostermeier, licensed veterinarian and advisor at Figo Pet Insurance.

OljaSimovic via iStock

Factors That Help Estimate Adult Size

Outside of breed, a few additional factors can help you figure out how big your puppy will get. These considerations include your pup’s parents, paw size, and gender. The timing of your dog’s spay or neuter can also play a part in your puppy’s final height and weight.

Parents

For all dogs, Dr. Ostermeier says looking at the parents will indicate where your pup’s adult size will land. Generally, puppies will not be larger than the biggest parent. If both parents are the same size, your puppy will likely follow suit.

However, this method becomes more speculative when the puppy’s parentage is unknown—common in shelters or rescues.

Paw size

Large paws usually suggest a bigger dog, says Dr. Johnson. If your puppy’s paws appear disproportionately large compared to their body, they probably have a lot more growing to do!

However, paw size isn’t a definitive guidepost. Some dogs naturally have larger or smaller feet relative to their body. So, while paw size offers clues, it shouldn’t be the sole factor in your estimations.

Gender

On average, male dogs are usually larger than females. Some breeds have a more significant size difference than others. For example, extra-large breeds will likely have a greater size difference between genders, while the difference between smaller breeds will be less. Of course, individual variations will affect the size of a male or female dog, along with their diet and overall health.

Timing of spay/neuter

While spaying and neutering your puppy is an important step in responsible pet ownership, the timing could affect your dog’s overall growth. One study linked neutering later in life (after 37 weeks) to slightly less growth.

Growth Periods

It can take anywhere between 6 to 24 months for puppy bones to fully develop. However, most breeds typically experience the most growth in their first 6 months of puppy life. As shown in the chart below, most puppies will reach at least 50% of their eventual body weight by the time they’re 6 months old, regardless of their breed size.

Once your puppy’s growth plates have stopped making new tissue, they become “closed” or wholly calcified, meaning their bones have stopped growing. However, even after their bones have fully developed, puppies will continue to put on fat and muscle, affecting their overall size.

Monitoring Your Puppy’s Weight

Just like humans, puppies can face health issues if their weight is too low or too high. According to Dr. Johnson, weight tracking helps ensure proper growth and development. To help catch any potential nutritional deficiencies or medical problems early on, consider these tips:

• Check your dog’s body score condition. You should be able to feel their ribs without excess fat covering them. Their waist should also be visible when viewed from above.
• Consult your vet. Dr. Ostermeier emphasizes the importance of keeping to regular veterinary visits, especially between 4 to 6 months of age. You can discuss any weight concerns and get professional guidance on feeding and nutrition.
• Adjust diet and exercise. Based on your findings, you may need to adjust your puppy’s diet or exercise to promote healthy growth. Your vet may recommend a special low-calorie diet or incorporating more exercise into your puppy’s routine.

In the end, all pups are pretty great—whether they wind up tiny peanuts or colossal companions. “Though you can’t exactly predict when your puppy is going to stop growing, or how big they’re going to end up—you can help them stay their happiest and healthiest throughout the journey,” Dr. Johnson concludes.

Further Reading

• How Long Is a Dog a Puppy?
• What to Expect With A New Puppy: The First 6 Months
• The Best Puppy Feeding Schedules By Age
• The New Puppy Checklist: Essentials for Pet Parents