Puppy Weight Calculator
Predict your puppy's adult weight using veterinary growth curve data. Enter your puppy's breed, age, and current weight to see how big they'll get.
Your Puppy
Projected Growth Curve
How We Predict Your Puppy's Adult Weight
Our puppy weight calculator uses the percentage-of-adult-weight method, which is based on decades of veterinary growth research. Puppies of different size categories reach predictable percentages of their adult weight at specific ages. By knowing your puppy's current weight and age, we can work backward to estimate their adult size.
The growth curve data powering this calculator comes from the WALTHAM Petcare Science Institute, which studied over 50,000 healthy puppies to create standardized growth charts. This data was further validated by Salt et al. (2017) in a study of 6 million veterinary patient records published in PLOS ONE.
Understanding Puppy Growth Patterns
Puppies do not grow at a constant rate. Growth is fastest in the first few months of life, then gradually slows as they approach adult size. Smaller breeds reach maturity much faster than larger breeds:
- Toy breeds (Chihuahua, Yorkie): Reach adult size by 8–10 months
- Small breeds (French Bulldog, Beagle): Full size by 10–12 months
- Medium breeds (Border Collie, Bulldog): Full size by 12–14 months
- Large breeds (Labrador, Golden Retriever): Full size by 14–18 months
- Giant breeds (Great Dane, Mastiff): May not reach full size until 18–24 months
Factors That Affect Adult Size
While genetics (breed) is the primary determinant of adult size, other factors play a role. Nutrition during the growth phase is critical — both underfeeding and overfeeding can affect final size and long-term health. Puppies that are spayed or neutered before full maturity may experience slightly delayed growth plate closure, potentially making them marginally taller but not significantly heavier.
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Sources & Methodology
- WALTHAM Petcare Science Institute — Puppy Growth Charts (waltham.com/resources/puppy-growth-charts)
- Salt, C., Morris, P.J., Wilson, D., Lund, E.M., & German, A.J. (2017). "Growth standard charts for monitoring bodyweight in dogs of different sizes." PLOS ONE, 12(9): e0182064
- AKC breed weight standards (akc.org/dog-breeds/)
This calculator provides estimates based on growth data from veterinary research (WALTHAM Petcare Science Institute). Actual adult weight may vary by ±20% based on genetics, nutrition, health, and other factors. This tool is for informational purposes only and does not replace veterinary guidance. Consult your veterinarian for personalized advice about your puppy's growth.
Puppy Weight Calculator FAQ
How accurate is a puppy weight calculator?
Puppy weight calculators based on growth curve data (like the WALTHAM charts used here) are generally accurate within 10–20% for purebred dogs. Mixed breeds have more variation. The prediction improves as your puppy gets older because there is less remaining growth to estimate. For the most accurate prediction, weigh your puppy regularly and consult your veterinarian.
How big will my puppy get?
Your puppy's adult size depends primarily on breed (genetics), sex, and nutrition. Small breeds (Toy, Small) typically reach full size by 10–12 months, medium breeds by 12–14 months, large breeds by 14–18 months, and giant breeds may not reach full size until 18–24 months. Male dogs are typically 10–15% heavier than females of the same breed.
When do puppies stop growing?
Toy and small breed puppies typically stop growing between 8–12 months. Medium breeds finish around 12–14 months. Large breeds continue growing until 14–18 months, and giant breeds (Great Danes, Mastiffs) may not reach full size until 18–24 months. Height growth usually stops before weight gain plateaus.
Does neutering or spaying affect my puppy's adult weight?
Neutering/spaying can cause a slight delay in growth plate closure, which may make your dog slightly taller. However, the effect on total adult body weight is typically minimal. Neutered/spayed dogs may be more prone to weight gain due to metabolic changes, so monitoring diet and exercise after the procedure is important.
What if my puppy is a mixed breed?
For mixed breed puppies, select "Mixed breed" or "I don't know" from the breed list and choose the size category that best matches one or both parents. If you know the parents' sizes, you can estimate which category fits best. DNA testing can also help identify breed mix and predict adult size more accurately.
Why is my puppy's growth different from the chart?
Individual puppies vary — genetics, nutrition, health status, and even litter size can affect growth rate. If your puppy is consistently gaining weight and meeting developmental milestones, slight deviations from the average curve are normal. Sudden growth stalls, rapid weight loss, or extreme deviations should be discussed with your veterinarian.