Puppy Adult Weight Predictor

How big will your puppy get? Predict their adult weight using their current age, weight and expected breed size — with a breakdown of their growth stages.

Puppy's current age (weeks)

Current weight (kg)

Breed size (expected adult size)

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Enter your puppy's age, weight and expected breed size to predict their adult weight.

Track every milestone. A puppy development book helps you log weight, vaccinations and key milestones from day one through to adult life.

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How Puppy Weight Prediction Works

The most reliable prediction method uses the puppy's weight at a known age and applies a breed-size growth curve. The formula varies by size class because large and giant breeds take much longer to reach adult weight — a Chihuahua is essentially adult at 9 months while a Great Dane may continue growing until 18–24 months.

The most commonly used formula: for medium breeds at 14 weeks, adult weight ≈ (current weight / 14) × 52. This is adjusted by breed size. Mixed breeds are harder to predict — a mid-point of apparent parent sizes is used. DNA tests give more precise breed composition and therefore better predictions.

Toy and small breeds reach adult weight by 9–12 months. Medium breeds by 12–15 months. Large breeds by 15–18 months. Giant breeds by 18–24 months — some continue gaining muscle until 3 years. Growth plates typically close 1–2 months after reaching adult height. Heavy exercise (running, jumping) should be limited until growth plates close to prevent orthopaedic damage.

Predictions are useful estimates with ±15–20% uncertainty for purebred dogs. Mixed breeds and unknowns can be significantly less predictable. The most accurate predictor of adult weight is the puppy's weight at 16 weeks — at this age, most puppies are between 50–60% of their adult weight (size-dependent). DNA breed testing significantly improves accuracy for mixed breeds.