Puppy Weight Calculator
How big will my puppy get? Enter age and current weight to estimate adult weight. Estimates come from vet-clinic weight records of millions of young dogs (the open Salt et al., 2017 dataset), not a one-size "double it at 16 weeks" rule.
Enter age (8–52 weeks) and weight to see an adult estimate and your puppy on the growth chart.
How the puppy size calculator works
Salt and colleagues (PLOS ONE, 2017) analysed bodyweights from more than 6 million young dogs seen at Banfield Pet Hospitals and published the underlying data. We took the weights of dogs under two years old from that open dataset (excluding visits recorded as thin or heavy) and, for six adult-size groups, worked out what percentage of their breed's average adult weight puppies typically weigh at each age. Your puppy's weight divided by that percentage gives the adult estimate.
The key finding: small dogs finish growing much sooner than big ones. Salt et al. note that very small dogs reach maturity at 8–12 months while larger breeds can take up to 24 months. In our summary, a typical toy-size puppy weighs about half its adult weight at 16 weeks, whereas a giant-breed puppy is only about a third of the way there.
| Adult size | 8 wk | 12 wk | 16 wk | 24 wk | 36 wk | 52 wk |
|---|---|---|---|---|---|---|
| Toy Under 6.5 kg (under 14 lb) | 27% | 38% | 51% | 70% | 84% | 91% |
| Small 6.5–9 kg (14–20 lb) | 25% | 36% | 50% | 70% | 84% | 91% |
| Medium 9–15 kg (20–33 lb) | 21% | 31% | 44% | 65% | 81% | 88% |
| Large 15–30 kg (33–66 lb) | 17% | 29% | 42% | 65% | 84% | 92% |
| Extra large 30–40 kg (66–88 lb) | 16% | 27% | 40% | 62% | 84% | 92% |
| Giant Over 40 kg (over 88 lb) | 13% | 23% | 35% | 57% | 80% | 91% |
Median weight as a percentage of the breed-average adult weight (weight at about 2 years). Our summary of the Salt et al. (2017) open dataset; see sources & method.
Why estimates are a range
- Individual variation. Even within a breed, healthy adults differ a lot. The band on the chart shows how wide normal is.
- Mixed breeds may follow neither parent's curve exactly. Pick "Not sure" and re-check every few weeks.
- Young puppies are harder to predict. The estimate firms up after about 16 weeks.
- Neutering timing made small differences to growth in the Salt study, but these were small compared with the differences between individual dogs.
Weight alone doesn't tell you whether a puppy is lean or overweight. Your vet checks body condition, and that matters more than hitting a number. See the full puppy growth chart by size for week-by-week weights.
Questions breeders ask
How big will my puppy get?
Enter your puppy's age and weight above. The calculator compares them with growth data from healthy puppies of similar adult size and estimates adult weight with a likely range.
Is the "double the weight at 16 weeks" rule accurate?
Only for some sizes. In the Salt et al. data, toy and small puppies are around half their adult weight at 16 weeks, but large and giant puppies are closer to 35–40%, so doubling would underestimate them.
At what age is a puppy fully grown?
Salt et al. note that very small dogs reach maturity at around 8–12 months, while larger breeds can take up to 24 months to reach adult weight.
Why does my puppy's estimate change between weeks?
Puppies grow in spurts and can drift between percentiles, especially when young. Re-check every few weeks; the estimate becomes more reliable after about 16 weeks.
My puppy is below the band. Should I worry?
Not necessarily. The band covers the middle 80% of healthy puppies, so some healthy puppies fall outside it. If your puppy is losing weight, not eating or seems unwell, see your vet.