Puppy Weight Calculator
How big will your puppy get? This calculator uses size-class growth curves — not the crude linear formula — because a Yorkie and a Great Dane grow on completely different schedules. Get the predicted adult weight, the full growth chart, and the age your dog will stop growing.
How the prediction works
Puppies don't grow linearly — they grow fast early, then flatten out. And the schedule depends on adult size: small breeds hit half their adult weight around 12–14 weeks and finish by 9–12 months, while giant breeds hit halfway around 5–6 months and keep going until 18–24 months. We take your puppy's age, look up what fraction of adult weight a puppy of that size class has typically reached, and divide the current weight by that fraction.
| Age | Toy/Small | Medium | Large | Giant |
|---|---|---|---|---|
| 8 weeks | ~27–30% | ~23% | ~20% | ~17% |
| 12 weeks | ~42–46% | ~36% | ~31% | ~27% |
| 6 months | ~82–87% | ~72% | ~64% | ~55% |
| 12 months | 100% | ~97% | ~92% | ~83% |
| Full grown | 9–12 mo | 12–15 mo | 15–18 mo | 18–24 mo |
The estimate carries a ±12% range — that's honest uncertainty for a home prediction. Parent size narrows it further: adult weight usually lands near the average of the parents, with males running to the upper end.
Puppy growth FAQ
When do puppies stop growing?
Toy/small: 9–12 months. Medium: 12–15 months. Large: 15–18 months. Giant: 18–24 months. Filling out (muscle and chest) continues after height stops.
Is "double the 4-month weight" accurate?
Only for medium breeds, roughly. Small breeds are already past 50% at 4 months; large and giant breeds are well short of it.
Do big paws mean a big dog?
It's folk wisdom with weak correlation. Age-adjusted weight and parent size predict far better.
My puppy is way off the estimate — should I worry?
First check the size class — that's the most common miss, especially with mixed breeds. Consistent weight loss, a pot-bellied look, or falling off a growth curve your vet is tracking are the actual red flags.
Why does adult size matter for food?
Large and giant breed puppies need large-breed puppy formulas — controlled calcium and calories reduce the risk of developmental joint disease. Overfeeding a fast-growing large breed is a real orthopedic risk.
Bigger dog, bigger vet bills — and premiums rise with age
Insuring a puppy young locks in lower rates and means nothing counts as pre-existing. Average dog coverage runs $62/month in 2026 — see real prices by provider.
Compare pet insurance prices →Related dog calculators
Method: size-class growth-curve interpolation consistent with published canine growth standards (WSAVA growth charts; Waltham puppy growth research). Last reviewed August 2026.