How this calculator works
Puppies of different adult sizes grow at different rates: toy and small breeds reach full size fast (as early as 6–9 months), while giant breeds keep growing for up to two years. Picking a specific breed sets the right growth curve automatically, based on that breed's typical size tier — or choose "mixed breed / not sure" and pick the closest size yourself. The calculator then uses typical growth-curve percentages — what share of adult weight a puppy has usually reached at a given age — to back into an estimated adult weight from your puppy's current weight and age.
Why this is only an estimate
Individual puppies vary, and mixed-breed puppies can be harder to predict than purebreds. Littermate size, sex, and genetics all play a role. Use this as a ballpark figure, and ask your vet for a more tailored estimate at checkups — they can track your puppy's growth curve directly.
We publish the exact growth curves behind this estimate, including the full data tables.
See the methodology →Sources
Quick reference: percent of adult weight by age
| Age (weeks) | Toy | Small | Medium | Large | Giant |
|---|---|---|---|---|---|
| 8 | 30% | 25% | 20% | 15% | 10% |
| 16 | 58% | 50% | 40% | 30% | 22% |
| 24 | 80% | 72% | 62% | 48% | 36% |
| 52 (1 yr) | 100% | 100% | 97% | 88% | 72% |
See the full week-by-week breakdown in the Puppy Growth Chart by Size.
Frequently asked questions
How accurate is this puppy weight calculator?
It's a general estimate based on typical growth curves for each size tier. Individual puppies vary due to genetics, littermate size, and sex, so treat the result as a ballpark rather than an exact prediction.
Can I estimate a mixed-breed puppy's adult weight?
Yes. Choose "mixed breed / not sure" and pick the closest adult size tier based on your puppy's current build, paw size, and parentage if known. It will be somewhat less precise than a known purebred, but still a useful ballpark.
At what age is a puppy considered full grown?
It depends heavily on adult size: toy breeds by around 10-11 months, small breeds by about a year, medium breeds by around 14 months, large breeds by around 18 months, and giant breeds not until close to 2 years old. See When Do Puppies Stop Growing? for the full breakdown.
Why do larger breeds take longer to reach adult size?
Larger breeds have more growth to complete overall, and their bones and joints develop over a longer window to support that eventual size. Growing too fast can stress developing joints, which is part of why controlled growth matters more for large and giant breed puppies. See How Big Will My Puppy Get? for more.