How Big Will My Puppy Get? Adult Size by Weight and Age
You can get a fair estimate of your puppy’s adult size from its weight now, its age and its size group (toy, small, medium, large or giant). Divide its weight by the share of adult weight a puppy of that size has usually reached at that age:
Adult weight ≈ weight now ÷ share of adult weight reached
The puppy weight calculator does this for you. For a pedigree puppy, the breed standard and the parents’ weights are often an even better guide.
How fast puppies grow
Puppies follow an S-shaped growth curve that flattens out as they reach adult size, and bigger breeds take longer. WALTHAM’s puppy growth charts, built from the weights of 50,000 healthy young dogs, note that:
- Small dogs (under 9 kg, about 20 lb) are full grown at about 12 months
- Dogs of 30–40 kg (about 66–88 lb) are full grown at about 18 months
- Giant breeds take almost two years
How much will my puppy weigh full grown?
- Weigh your puppy and note its age in weeks.
- Pick its size group. For a pedigree, use the breed standard; the AKC lists adult weight ranges for every recognised breed. For a mixed breed, the parents’ weights (if you know them) are the best clue.
- Compare with a growth chart. The WALTHAM Puppy Growth Charts have 14 charts for male and female puppies in seven size groups, from 12 weeks old to adulthood, and show the adult weight a puppy on a given curve is heading for.
- Or use the calculator. The puppy weight calculator divides the weight now by the share of adult weight a puppy of that size and age has usually reached.
The younger the puppy, the less certain any estimate is. Re-check every month or so: estimates get better as your puppy gets older.
How big will my puppy be based on weight?
Weight alone isn’t enough: you also need the age and the size group. The same weight can belong to a nearly grown small dog or a young giant-breed puppy.
Clues that don’t work well
- Paw size. Big paws are a fun clue, but paw size varies between breeds and even between puppies in the same litter.
- “Double the 4-month weight.” Rules like this only fit some sizes, because small breeds finish growing much sooner than large and giant breeds.
- Guessing a mixed breed’s parents. If you don’t know the parents, the weight-and-age method is the most useful clue you have.
What you can do with the estimate
- Buy the right crate. Get a crate for the adult size and use a divider while your puppy is small. The dog crate size calculator helps.
- Feed for growth. The expected adult weight is part of the puppy feeding formula in the puppy food calculator.
- Grow big puppies slowly. Large and giant breed puppies should not be pushed to grow fast.
Estimate your puppy’s adult size now with the puppy weight calculator.
Sources: WALTHAM Petcare Science Institute puppy growth charts; Salt C. et al. (2017) Growth standard charts for monitoring bodyweight in dogs of different sizes, PLOS ONE 12(9): e0182064; American Kennel Club breed pages. General information, not veterinary advice.