The Scientifically Grounded
Puppy Growth & Weight Predictor

Standard internet rules like 'Weight at 16 weeks × 2' assume linear growth. In reality, canine growth is non-linear (sigmoidal). Toy breeds achieve 50% of adult weight by 12–14 weeks and finish growing by 9–10 months, whereas Giant breeds reach 50% at 24–28 weeks and grow for up to 24 months. Our calculator uses peer-reviewed WALTHAM growth standard curves (Salt et al., 2017) and 250+ AKC breed anchors to compute mathematically calibrated confidence intervals.

For puppies 12 weeks of age and older, the prediction is typically accurate within ±5% to ±10% of their final adult weight. Adding the biological mother and father's adult weights further narrows this confidence interval. For puppies under 8 weeks old, maternal factors make predictions rougher estimates.

Yes! If your puppy is a mixed breed or rescue without known parents, simply leave the breed field blank. Our engine compares your puppy's current age and weight against the 5 standardized biological canine growth curves (Toy, Small, Medium, Large, Giant) to determine their exact growth velocity and projected adult size category.

We follow World Small Animal Veterinary Association (WSAVA) and National Research Council (NRC) equations: Resting Energy Requirement (RER) is calculated as 70 × (weight in kg)^0.75. We then apply age-specific multipliers (3.0× RER for puppies 0–4 months, 2.0× RER for 4–12 months) to ensure optimal skeletal and muscular development without overfeeding.

Maturity timing depends heavily on adult breed size: Toy and Small dogs reach full adult size between 8 and 12 months; Medium dogs finish between 12 and 14 months; Large breeds finish between 14 and 18 months; and Giant breeds (90+ lbs) continue building bone density and muscle mass until 18 to 24 months.

Yes, 100% free with no registration, no email paywall, and no sign-up required. All calculations run client-side directly inside your web browser.