Puppy Weight Calculator
How big will
my puppy get?
Built on growth records from over 100,000 healthy puppies in the WALTHAM / Banfield growth study, not a "double the 16-week weight" rule of thumb.
Between 8 and 52 weeks. 3 months ≈ 13 weeks, 6 months ≈ 26 weeks.
Not sure? Pick a breed below, or use the size of the parents.
Estimated adult weight
42lbs
At 12 weeks, a large-breed puppy has reached about 28% of its adult weight. Most reach 90% around 42 weeks (about 10 months).
The range covers the middle half of puppies in the study. Mixed breeds, very young puppies and giant breeds vary more. Not veterinary advice. Ask your vet if your puppy seems too thin or heavy.
Puppy growth chart: percent of adult weight by age
Each cell shows how much of its adult weight a typical puppy has reached at that age. To estimate adult weight by hand, divide your puppy's current weight by the percentage. A 12-week-old large-breed puppy at 12 lbs is at about 28%, so 12 ÷ 0.28 ≈ 43 lbs.
| Age | Small under 20 lbs | Medium 20–33 lbs | Large 33–66 lbs | X‑Large 66–88 lbs | Giant 88+ lbs |
|---|---|---|---|---|---|
| 8 wks 2 mo | 30% | 22% | 17% | 16% | 14% |
| 10 wks | 35% | 28% | 22% | 21% | 18% |
| 12 wks 3 mo | 41% | 33% | 28% | 27% | 24% |
| 14 wks | 46% | 39% | 34% | 32% | 29% |
| 16 wks 4 mo | 51% | 44% | 41% | 38% | 35% |
| 20 wks 5 mo | 60% | 55% | 53% | 50% | 47% |
| 24 wks 6 mo | 68% | 65% | 63% | 60% | 58% |
| 30 wks 7 mo | 78% | 76% | 76% | 73% | 72% |
| 36 wks 8 mo | 85% | 84% | 85% | 82% | 82% |
| 43 wks 10 mo | 90% | 90% | 91% | 89% | 89% |
| 52 wks 12 mo | 95% | 95% | 96% | 95% | 95% |
Small breeds start out relatively bigger: at 8 weeks they already weigh about 30% of their adult weight, while giant breeds are at about 14%. That's why the same weight means very different things depending on size.
When do puppies stop growing?
In the growth data behind this calculator, puppies of every size reached about 90% of their adult weight around 10 months and about 95% around 12 months. After that, most dogs gain only a little.
| Adult size | 75% grown | 90% grown | 95% grown |
|---|---|---|---|
| Small under 20 lbs | ~7 mo | ~10 mo | ~12 mo |
| Medium 20–33 lbs | ~7 mo | ~10 mo | ~12 mo |
| Large 33–66 lbs | ~7 mo | ~10 mo | ~11.5 mo |
| X‑Large 66–88 lbs | ~7.5 mo | ~10 mo | ~12.5 mo |
| Giant 88+ lbs | ~7.5 mo | ~10 mo | ~12 mo |
Bigger breeds still have more to do in that time. A giant puppy multiplies its 8-week weight about 7 times, a small one about 3 times. Large and giant breeds also keep filling out slowly into their second year, so treat 12 months as "mostly grown", not "finished".
When a dog counts as an adult for food and care is a separate question. Our dog life stages table shows when each size moves from puppy to young adult.
How this calculator works
We used the public dataset from Salt et al. (2017), Growth standard charts for monitoring bodyweight in dogs of different sizes (PLOS ONE), which covers purebred dogs seen at Banfield Pet Hospitals in the US between 1994 and 2013. We kept visits where the vet recorded a normal body condition, then compared each puppy's weight to the average adult weight of its breed.
For each size group we fitted a smooth growth curve to the weekly medians and set the two-year weight to 100%. The likely range in your result is the spread between the 25th and 75th percentile of individual puppies at the same age. Data: University of Liverpool data catalogue, CC BY 4.0. The original study did not publish curves for dogs over 40 kg (88 lbs), so treat Giant results with extra caution.
Frequently asked questions
Does "double the 16-week weight" work?
Only for small breeds. At 16 weeks, small puppies are about 51% of their adult weight, so doubling works. Large puppies are about 41% (multiply by 2.5) and giant puppies about 35% (multiply by 2.8).
How accurate is a puppy weight calculator?
It gives a reasonable range, not a promise. Half of the puppies in the study ended up inside the range we show. Predictions get tighter as your puppy gets older, so re-check every few weeks.
My puppy is a mixed breed. Which size should I pick?
Use the expected adult size, based on the parents if you know them, or your vet's best guess. If you're between two sizes, try both and compare. Mixed breeds tend to vary more than the range shows.
At what age is a puppy fully grown?
Most puppies reach about 90% of adult weight around 10 months and 95% around 12 months. Large and giant breeds keep filling out slowly into their second year.
Should I worry if my puppy is outside the range?
Not necessarily. Genetics, sex and neutering all shift growth. What matters more is body condition: you should be able to feel the ribs without seeing them. If your puppy looks thin or round, ask your vet.
Can you tell how big a puppy will get by its paws?
Not reliably. Big paws can hint at a bigger dog, but paw size varies a lot between breeds and even littermates, and there's no study that turns paw size into an adult weight. Current weight at a known age, which this calculator uses, is a much better guide.
Do male puppies grow bigger than females?
In many breeds, yes. Breed standards often list males 10–20% heavier, for example 65–80 lbs vs 55–70 lbs for Labrador Retrievers. If you pick a breed above, we show the typical male and female adult weights next to your estimate.
Does neutering or spaying change how big my puppy gets?
It can change shape more than size. Dogs neutered before their growth plates close may end up slightly taller. Weight gain after neutering usually comes from lower energy needs, so watch portions and body condition rather than the scale alone.