Dog Age ToolsHow big will my puppy get?
Weigh your puppy and note the age in weeks. Pick the size class you expect. The tool divides today's weight by the share of full size a puppy that size has usually reached at that age. For example, a medium puppy at 12 weeks is about 39 percent grown, so 10 pounds now points to about 26 pounds as an adult.
How the estimate works
Puppies do not grow at a steady rate. They gain slowly at first, then very fast, then slowly again as they near full size. That pattern is an S shaped curve. In 2004, researchers at the WALTHAM Centre for Pet Nutrition weighed 173 puppies from 12 breeds every week and fit this kind of curve to each breed. The study was published in the Journal of Nutrition.
Share grown = 1 ÷ (1 + e^(−k × (weeks − half)))
Here "half" is the age when a puppy reaches 50 percent of its grown weight. The value k sets how fast the curve rises. We took both numbers from the study's table and averaged the breeds in each size class. Then the adult estimate is simply weight now ÷ share grown.
Puppy growth chart by size
This table shows the share of full size a typical puppy has reached at each age. Use it as a puppy weight chart: multiply the percent by the expected adult weight.
| Weeks | Toy | Small | Medium | Large | Giant |
|---|---|---|---|---|---|
| 8 | 39% | 23% | 24% | 19% | 16% |
| 12 | 53% | 36% | 39% | 29% | 25% |
| 16 | 68% | 52% | 56% | 41% | 36% |
| 20 | 79% | 68% | 72% | 55% | 50% |
| 24 | 87% | 80% | 84% | 68% | 63% |
| 30 | 94% | 92% | 94% | 83% | 79% |
| 36 | 98% | 97% | 98% | 92% | 90% |
| 44 | 99% | 99% | 99% | 97% | 96% |
| 52 | 100% | 100% | 100% | 99% | 99% |
| 65 | 100% | 100% | 100% | 100% | 100% |
Half grown and fully grown ages from the study
| Breed | Size | Adult kg | Weeks to 50% | Weeks to 99% |
|---|---|---|---|---|
| Papillon | Toy | 2.2 | 11.1 | 41.7 |
| Cairn Terrier | Small | 6.3 | 15.5 | 42.9 |
| Miniature Schnauzer | Small | 7.0 | 14.1 | 41.3 |
| Cocker Spaniel | Small | 10.2 | 16.6 | 46.6 |
| English Springer Spaniel | Medium | 14.8 | 14.3 | 39.4 |
| Beagle | Medium | 17.4 | 14.8 | 41.9 |
| Labrador Retriever | Large | 28.1 | 18.6 | 52.1 |
| Newfoundland | Giant | 43.3 | 18.5 | 46.1 |
| Great Dane | Giant | 51.1 | 18.1 | 52.1 |
| Irish Wolfhound | Giant | 52.4 | 19.1 | 49.1 |
| St. Bernard | Giant | 65.2 | 21.9 | 56.7 |
| English Mastiff | Giant | 66.9 | 22.9 | 65.2 |
One kilogram is about 2.2 pounds. The study tracked toy to medium dogs to about 12 months and large and giant dogs to about 18 months.
Which size class should I pick?
Pick the class that matches the expected adult weight of the breed or of the parents. If you have the AKC breed standard, use the weight it lists. For a mixed breed, pick the class of the larger parent, then compare it with the next class down. Your weigh ins over the next few weeks will show which curve fits.
- Toy: Chihuahua, Yorkie, Papillon
- Small: Shih Tzu, French Bulldog, Miniature Schnauzer, Cocker Spaniel
- Medium: Beagle, English Springer Spaniel
- Large: Labrador, Golden Retriever, German Shepherd
- Giant: Great Dane, Mastiff, St. Bernard, Newfoundland
Tips for tracking growth
- Weigh at the same time of day, before a meal, every one or two weeks.
- Small puppies are easy on a kitchen scale. For big puppies, weigh yourself holding the puppy, then subtract your own weight.
- Plot each weigh in. A healthy puppy usually stays near the same curve.
- Ask your vet about body condition, not just weight. A puppy can be heavy for its age and still be lean, or the other way around.
Large veterinary datasets support this kind of tracking. A 2017 study in PLOS ONE used records from more than 6 million young dogs at US vet clinics to build growth standard charts. It found that growth could be described well with size groups rather than one chart per breed.
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FAQ
How accurate is a puppy weight calculator?
It gives a fair estimate, not a promise. Puppies of the same breed and age can still end up at different adult sizes. The estimate is best between 12 and 30 weeks of age. It gets less reliable if your puppy is sick, too thin or overweight.
At what age is a puppy half its adult weight?
In the Hawthorne study, toy dogs hit half their grown size at about 11 weeks. Small and medium breeds got there at about 14 to 17 weeks. Large and giant breeds took about 18 to 23 weeks.
When do dogs stop growing?
Most small and medium dogs reach 99 percent of full size at about 9 to 11 months. Labs took about 12 months in the Hawthorne study. Giant breeds such as Mastiffs took 11 to 15 months.
Can paw size tell me how big my puppy will get?
We found no peer reviewed study that links paw size to grown size. Weight at a known age, plus the size of the parents, is a better guide.
What if I have a mixed breed puppy?
Pick the size class that you expect based on the parents. If you do not know them, try two classes and look at both results. Then weigh your puppy every two weeks and check that the dots follow the curve.
Should I feed more to make my puppy bigger?
No. The Hawthorne study notes that overfeeding leads to obesity, and in large breeds it also causes bone and joint problems. Ask your vet how much to feed.
References
- Hawthorne A.J. et al. (2004). Body weight changes during growth in puppies of different breeds. Journal of Nutrition 134(8)
- Salt C. et al. (2017). Growth standard charts for monitoring bodyweight in dogs of different sizes. PLOS ONE
- Caring for senior cats and dogs, American Veterinary Medical Association