Puppy Weight Calculator
Enter your puppy’s weight, age in weeks and size (or breed). We divide today’s weight by the share of adult weight a puppy of that size has usually reached at that age, using growth curves from a study of 12 breeds.
Example: a 12-week-old large-breed puppy weighing 7.5 kg (16.5 lb) is at about 29% of adult weight, so it will probably weigh about 26 kg (57 lb) as an adult.
How it works
Puppies of different sizes grow at different speeds. In a study of 12 breeds, Hawthorne et al. (2004) fitted each breed’s growth to an S-shaped (logistic) curve and reported two ages for it: when puppies reached 50% of their adult weight (x0) and when they reached 99% (T99).
share of adult weight at t weeks = 1 ÷ (1 + e^(−k × (t − x0))) k = ln(99) ÷ (T99 − x0) adult weight ≈ current weight ÷ share
For each size class we use the average x0 and T99 of the study breeds in that class (table below). The result is shown with a ±10% range. If you pick a breed, we also compare the estimate with the AKC breed standard.
How to estimate your puppy's adult weight
- Weigh your puppy. Use a bathroom scale (weigh yourself holding the puppy, then subtract your own weight) or ask your vet clinic.
- Enter the age. Type the age in weeks, or pick the birthday and the calculator works out the weeks.
- Choose the breed or size. Pick the breed, or for a mixed breed choose the size you expect: toy, small, medium, large or giant.
- Read the estimate and range. The headline is the most likely adult weight; the range (±10%) allows for normal variation. Re-check every few weeks.
Growth curve by size
| Size | Study breeds (Hawthorne 2004) | 50% of adult weight at (weeks) | 99% at (weeks) | Share at 12 wk | 16 wk | 26 wk | 36 wk |
|---|---|---|---|---|---|---|---|
| Toy | Papillon | 11.1 | 41.7 | 53% | 68% | 90% | 98% |
| Small | Cocker Spaniel, Miniature Schnauzer, Cairn Terrier | 15.4 | 43.6 | 36% | 52% | 85% | 97% |
| Medium | Beagle, English Springer Spaniel | 14.6 | 40.6 | 39% | 56% | 88% | 98% |
| Large | Labrador Retriever | 18.6 | 52.1 | 29% | 41% | 73% | 92% |
| Giant | English Mastiff, St Bernard, Irish Wolfhound, Great Dane, Newfoundland | 20.1 | 53.8 | 25% | 36% | 69% | 90% |
x0 and T99 are averages of the study breeds in each class. Shares are computed from the curve.
Frequently asked questions
How accurate is a puppy weight calculator?
It gives a reasonable estimate, not a promise. Real puppies vary a lot, even within one litter, which is why we show a ±10% range. Estimates get better as your puppy gets older, so re-check every few weeks and talk to your vet about your puppy’s body condition.
When do puppies stop growing?
In the growth study we use, toy and small breeds reached 99% of adult weight at about 42–44 weeks (around 10 months), medium breeds at about 41 weeks, Labradors at about 52 weeks and giant breeds at about 54 weeks on average, with some giant breeds (such as Mastiffs) taking over 65 weeks.
What about the “weight ÷ age in weeks × 52” rule?
It is a popular rule of thumb, not a study result. It assumes puppies grow at a steady rate all year, which they do not, so it tends to overestimate adult weight for small breeds and young puppies. We show a growth-curve estimate instead.
My puppy is a mixed breed. Which size should I pick?
Pick the size you expect from the parents, if you know them. You can also use the parents’ weights in the dog size calculator. If you are unsure, compare the toy, small, medium, large and giant results and ask your vet.
Why does it say my puppy is too young?
Growth is hard to predict in the first weeks, and the studies we use start at about 8 weeks (Hawthorne) and 12 weeks (Salt). Come back when your puppy is at least 8 weeks old.
When to see a vet
- Your puppy is losing weight, or is not gaining for more than a week or two.
- You can see the ribs, hips or spine clearly, or you can’t feel the ribs at all.
- Vomiting, diarrhoea, low energy or not eating for more than a day.
- A large or giant puppy is growing very fast. Ask about the right food and feeding amount.
This is an estimate for general information, not veterinary advice. Every pet is different. Ask your veterinarian before changing your pet's diet, especially for puppies, kittens, pregnant or nursing pets, seniors, or pets with health conditions.
Sources
- Hawthorne AJ, Booles D, Nugent PA, Wilkinson J, Gettinby G. Body-weight changes during growth in puppies of different breeds. J Nutr. 2004;134(8 Suppl):2027S–2030S. doi.org/10.1093/jn/134.8.2027S
- Salt C, Morris PJ, German AJ, Wilson D, et al. Growth standard charts for monitoring bodyweight in dogs of different sizes. PLOS ONE. 2017;12(9):e0182064. doi.org/10.1371/journal.pone.0182064
- American Kennel Club. Dog breed pages (breed-standard height, weight and life expectancy), accessed 20 October 2026. www.akc.org/dog-breeds/
- WSAVA Global Nutrition Committee. Global Nutrition Guidelines and toolkit (body condition score charts). wsava.org/global-guidelines/global-nutrition-guidelines/
Full methodology: sources and methodology. Last reviewed 20 October 2026.