Puppy Weight Calculator

How the puppy weight calculator works

A puppy weight calculator is a free online tool that estimates a dog's adult weight from its breed, current age and current weight.

Adult weight ≈ current weight ÷ growth completion at this age. Puppies of a given size class reach a predictable fraction of their adult weight at each age. The tool looks up that fraction for your puppy's size class and current age, then divides current weight by it to project the adult figure. This percentage-of-adult-weight method is more accurate than the older linear rule.

For comparison, the simple linear rule is Adult weight = (current weight ÷ current age in weeks) × 52. It works loosely for medium breeds mid-growth but over- or under-shoots for toy and giant breeds, which is why this tool uses size-class growth curves instead.

Quick breed rules of thumb owners often use (rough approximations only):

• Weight at 6 weeks × 4 ≈ adult weight (toy & small breeds).
• Weight at 8 weeks × 3 ≈ adult weight.
• Weight at 12 weeks × 2 ≈ adult weight.
• Weight at 6 months × 2 ≈ adult weight (medium & large breeds).

How big will my puppy get?

Breed size class is the strongest predictor of your puppy's adult weight. Breed standards from bodies like the American Kennel Club (AKC) define the typical adult range for each breed. Enter your puppy in the calculator above for an estimate; typical adult weight ranges by size class are:

• Toy (Chihuahua, Yorkshire Terrier): under ~12 lb (5.5 kg).
• Small (French Bulldog, Cavalier King Charles Spaniel): ~12-25 lb (5.5-11 kg).
• Medium (Border Collie, Staffordshire Bull Terrier): ~25-50 lb (11-23 kg).
• Large (Labrador Retriever, German Shepherd): ~50-90 lb (23-41 kg).
• Giant (Great Dane, Mastiff): 90 lb+ (41 kg+).

When do puppies stop growing?

Smaller breeds finish growing sooner than larger ones. Expected age at full size by breed size class:

• Toy: 8-10 months.
• Small: 10-12 months.
• Medium: 12-14 months.
• Large: 14-18 months.
• Giant: 18-24 months.

Puppy weight chart by age

Estimated weight for a medium-breed puppy by age, generated from the growth model above. Pick a breed in the calculator to update this chart. Male and female columns apply a typical ±6% sex difference. Figures are estimates, not breed standards.

Factors that affect your puppy's adult size

• Genetics / breed: the dominant factor; parent size is the best real-world predictor.
• Nutrition during the growth phase: both underfeeding and overfeeding change the trajectory; large-breed puppies should not grow too fast.
• Sex: males of most breeds finish slightly heavier than females.
• Desexing timing: can nudge growth-plate closure, a minor effect versus breed.
• Health: illness or parasites during growth can slow development.

When to worry about your puppy's weight

Most puppies track their growth curve within about ±15%. Check with your vet if you notice weight loss or a stalled weight before 12 months, ribs and spine that look very prominent, or a puppy so round you can't feel its ribs.

Vets grade body shape with the body condition score (BCS), a 9-point scale where 4-5 out of 9 is ideal: you should feel the ribs easily under a thin layer of fat and see a waist from above. The WSAVA body condition guidelines describe the full scale.

Large and giant breeds need extra care: growing too fast raises the risk of developmental orthopedic disease (DOD), so large-breed puppies should be kept lean on a large-breed puppy diet rather than over-fed to "catch up".

Sources & methodology

Growth-completion curves in this tool are modelled on published canine growth research and standard breed maturity timelines:

• Salt C, et al. (2017). "Growth standard charts for monitoring bodyweight in dogs of different sizes." PLOS ONE 12(9): e0182064.
• WALTHAM Petcare Science Institute: puppy growth charts and size-class references.
• Breed size classifications cross-referenced with recognised kennel-club breed standards, including the American Kennel Club (AKC).
• WSAVA Global Nutrition Committee: body condition score (9-point) guidelines.