How this predictor works
Puppies of different sizes don't just grow to different weights — they grow on different schedules. A Yorkie is nearly done growing at 9 months; a Great Dane keeps going toward its second birthday. This tool uses typical growth curves — the fraction of adult weight a puppy has reached at a given age — for each size class:
| Age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 8 weeks | ~32% | ~25% | ~20% | ~15% |
| 12 weeks | ~48% | ~40% | ~33% | ~26% |
| 16 weeks | ~62% | ~53% | ~45% | ~37% |
| 6 months | ~85% | ~78% | ~70% | ~60% |
| Adult by | 9–12 mo | ~12 mo | 15–18 mo | 18–24 mo |
Your puppy's projected adult weight is simply current weight ÷ growth fraction. We show a ±12% range because individual puppies genuinely vary — and for mixed breeds, treat the range as generous.
One thing that matters more than the prediction: don't rush growth. Overfeeding puppies — especially large and giant breeds — is linked to joint problems later. Feed to a lean body condition using our calorie calculator as a starting point, and let genetics set the final size.
Frequently asked questions
How big will my 12-week, 6 kg puppy get?
If it's a medium breed, roughly 15 kg as an adult (range ~13–17 kg) — at 12 weeks a medium puppy is near 40% of adult weight. The same 6 kg at 12 weeks in a giant breed projects to around 23 kg, because giants are only ~26% grown at that age.
Is "double the weight at 4 months" accurate?
Only as a very rough rule for medium breeds — at 16 weeks a medium puppy is around half its adult weight. It overestimates small breeds (already ~62% grown) and underestimates giants (~37%). Size-specific curves do better.
My puppy is above/below the curve — should I worry?
Steady growth along its own track matters more than any single number. If your puppy is losing weight, not gaining for weeks, or visibly ribby or pudgy, that's a vet conversation rather than a calculator problem.