How big will my puppy get?
Pick your puppy's size band (most owners know the parents' size or have a breeder estimate). Enter current age + weight. We project adult weight and show key growth milestones along the way.
Puppy growth calculator
Project your puppy's adult weight from current age + weight + size band. Growth curves are sourced from AAHA + Royal Canin breed-size growth standards.
Growth milestones
| Age | Estimated weight |
|---|
Puppy supplies worth having
AffiliatePuppy-pads for the first 3–4 months, a puzzle feeder to slow down fast eaters and add mental stimulation.
Disclosure: As an Amazon Associate we earn from qualifying purchases — at no extra cost to you. Affiliate revenue doesn't influence the math or recommendations on this site; every product listed is one we'd suggest regardless. See editorial policy for the full position.
- Amazon Basics Leak-Proof Puppy Training Pads (regular 22"×22", 100 ct)$20–32Bulk pads for the first 3-4 months of housetraining. 5-layer quick-dry design. Amazon-FBA, evergreen ASIN.
- Outward Hound Nina Ottosson Dog Twister Puzzle$15–25Mental enrichment + slows fast eaters. Good intermediate-level (Level 3) puzzle.
How puppies grow
Puppy growth isn't linear — it accelerates in the first 3–4 months, then slows dramatically. Smaller breeds finish growing faster (toy breeds reach adult weight around 9–10 months); giant breeds keep growing well past their first birthday (18–24 months for full muscle/skeletal maturity).
Size bands and adult-weight ranges
| Band | Adult weight | Mature at | Examples |
|---|---|---|---|
| Toy | 1.5–10 kg | ~10 mo | Chihuahua, Yorkie, Pomeranian |
| Small | 9–15 kg | ~12 mo | Beagle, French Bulldog, Cocker Spaniel |
| Medium | 15–25 kg | ~13 mo | Border Collie, Australian Shepherd |
| Large | 25–45 kg | ~16 mo | Labrador, Golden, German Shepherd |
| Giant | 45+ kg | ~22 mo | Great Dane, Mastiff, Saint Bernard |
The over-feeding trap (especially for large/giant breeds)
It's intuitive to feed a fast-growing puppy more food. For large and giant breeds, it's also dangerous. Excess calories accelerate growth in a way that increases the risk of developmental orthopedic disease (hip dysplasia, OCD, elbow dysplasia). Stick to the bag's puppy feeding chart for your projected adult weight (or use the dog calorie calculator for precise daily kcal), and aim for the *lean* end of normal body condition — slightly visible ribs is correct.
Sources: AAHA Canine Life Stage Guidelines (2019). Royal Canin growth standard charts. Hawthorne AJ et al., "Body-weight changes during growth in puppies of different breeds," J Nutr (2004). AAHA / AAFP are US veterinary-association bodies; UK readers see equivalent BSAVA / RCVS guidance, Australian readers see AVA, Canadian readers see CVMA — same fundamental veterinary science.
Frequently asked questions
How accurate is this calculator?
Within roughly ±15% for typical-breed puppies in the right size band. Mixed-breed puppies have wider variance — paw size and parents' weight are the best predictors when the breed is unknown. Use this as a planning estimate, not a guarantee. Re-run every 2–4 weeks during rapid growth (under 6 months) for tighter projections.
What if I don't know my puppy's adult size?
For mixed-breed puppies, paw size is a rough proxy — big-pawed puppies generally become big dogs. Veterinarians often DNA-test or estimate from observable traits. The shelter or breeder usually has a best guess. When in doubt, pick the band that matches the "bigger parent" if you know one.
When should I switch from puppy food to adult food?
When the puppy is at ~90% of expected adult weight. For toy breeds that's 8–9 months; for giant breeds 14–18 months. Switching too early risks developmental issues (especially in large/giant breeds, where joint development extends beyond 18 months). Switching too late risks excess weight gain.
My puppy seems much smaller/bigger than the projection. Should I worry?
If the size gap is significant, see a vet. Common causes for unusually small puppies: parasites (very common), congenital portosystemic shunt, runt-of-litter syndrome. Common causes for unusually large puppies: over-feeding (most common), large-for-breed lineage. A vet can rule out the medical causes quickly with bloodwork and a physical.
How fast should my puppy gain weight?
Roughly: 1–4 lb per month for toy/small breeds; 3–8 lb per month for medium/large; 6–15 lb per month for giant. Faster than that suggests over-feeding (which causes orthopedic disease in large breeds). Slower than that warrants a vet check — especially in puppies under 4 months.