Puppy Growth Calculator
Estimate your puppy's adult weight based on their current weight and age, using the vet-cited "weight at 16 weeks x2" rule of thumb.
Awaiting Details
Enter your puppy's weight and age to see their estimated adult weight.
How It Works & The Growth Formula
VCA Animal Hospitals and the American Kennel Club cite a simple rule of thumb: a puppy's weight at 16 weeks (4 months) old, doubled, gives a rough estimate of their adult weight. This works best for medium and large breed puppies.
This calculator projects your puppy's current weight to what it would be at 16 weeks, then applies the x2 rule. It's a general estimate, not a guarantee -- individual growth varies by breed, genetics, and nutrition. Toy breeds mature faster and giant breeds keep growing well past a year, so this rule is least reliable for those extremes.
Frequently Asked Questions
How accurate is the 'weight at 16 weeks x2' rule?
It's a widely cited rule of thumb from veterinary sources like VCA Animal Hospitals and the AKC, and it works reasonably well for medium and large breed puppies weighed between 8-20 weeks old. It's less reliable for toy/small breeds (who mature faster) and giant breeds (who keep growing well past a year).
Why does my puppy's estimate seem too high or low?
Individual growth varies by genetics, nutrition, and health. This is a general estimate, not a guarantee -- your breeder's pedigree history and your vet's assessment of your puppy's frame size are more reliable for predicting adult size.
When does my puppy stop growing?
Small breeds typically reach adult weight by 9-10 months, medium breeds by about 12 months, and large or giant breeds can keep filling out until 18-24 months old.
Should I feed my puppy differently while growing?
Yes -- growing puppies need more calories per kg of body weight than adult dogs. Use our Puppy & Kitten Feeding Calculator to estimate their daily calories and portion size.
Medical Disclaimer
This tool provides general, educational estimates and is not a substitute for professional veterinary advice, diagnosis, or treatment. This tool provides a rough estimate based on a general rule of thumb, not a guarantee of your puppy's future size. Always consult your veterinarian about your pet's specific health needs before making changes to their diet, water intake, or care routine.
Related Tools
Growth Chart
Visualize expected weight curves by breed size.
Puppy & Kitten Feeding Calculator
Calorie and portion needs for growing pets.
Dog Age Calculator
Convert your dog's age to human years.
Pregnancy & Gestation Calculator
Estimate a due date from the breeding date.
How This Calculator Works
Read the full breakdown of the formula, sources, and how to interpret your result.