Puppy Weight Calculator

How to Predict Your Puppy's Adult Weight

This puppy weight calculator predicts your dog's adult weight from its current weight, age, and breed size. The most reliable estimation method divides current weight by the puppy's age in weeks, then multiplies by the breed's weeks to maturity — this proportional formula works because puppy growth is roughly linear during the early months of life.

Maturity timelines by breed size:

• Toy breeds (under 10 lbs adult): Fully grown around 52 weeks (12 months)
• Small breeds (10–25 lbs adult): Fully grown around 52 weeks (12 months)
• Medium breeds (25–60 lbs adult): Fully grown around 78 weeks (18 months)
• Large breeds (60–100 lbs adult): Fully grown around 104 weeks (24 months)
• Giant breeds (100+ lbs adult): Fully grown around 130 weeks (30 months)

This formula is most accurate when used between 8 and 16 weeks of age, before growth rates begin to diverge significantly from the early linear pattern.

Puppy Weight Chart by Breed Size

The table below shows typical weight ranges at key developmental stages for each breed size. These are averages — individual dogs will vary based on genetics, litter size, diet, and health.

• Toy breeds: 8 wks: 1–2 lbs | 16 wks: 2–3 lbs | 6 mo: 3–5 lbs | Adult: 4–10 lbs
• Small breeds: 8 wks: 3–5 lbs | 16 wks: 6–9 lbs | 6 mo: 8–14 lbs | Adult: 10–25 lbs
• Medium breeds: 8 wks: 8–12 lbs | 16 wks: 15–22 lbs | 6 mo: 25–40 lbs | Adult: 25–60 lbs
• Large breeds: 8 wks: 12–20 lbs | 16 wks: 25–40 lbs | 6 mo: 50–70 lbs | Adult: 60–100 lbs
• Giant breeds: 8 wks: 15–25 lbs | 16 wks: 35–60 lbs | 6 mo: 70–110 lbs | Adult: 100–200 lbs

When Do Puppies Stop Growing?

Puppies grow fastest in their first 6 months of life, with growth slowing significantly after that. However, "full grown" and "full weight" are different milestones — many large and giant breeds will reach their full height before they fill out to their adult weight.

For giant breeds like Great Danes, Saint Bernards, and Mastiffs, the growth plates (soft areas at the end of bones where new bone tissue is produced) may not fully close until 18–24 months. This is why veterinarians recommend keeping giant breed puppies on lower-calorie large-breed puppy food and avoiding high-impact activities like running on hard surfaces until they are at least 18 months old.

Small and toy breed puppies, by contrast, grow up quickly — many are physically mature by 8–10 months. Their rapid growth means it is easier to overfeed them as puppies, leading to weight-related joint problems later in life.

Factors That Affect a Puppy's Adult Weight

Beyond breed genetics, several factors influence how large a puppy will ultimately grow:

• Parent weights: The single best predictor — if you know both parents' weights, average them for a good estimate.
• Nutrition: Puppies fed a high-quality diet appropriate for their size grow to their genetic potential. Malnourishment can stunt growth; overfeeding can cause excess fat gain and joint stress.
• Spay/neuter timing: Neutering before growth plates close (early in large breeds) may slightly increase final size, as sex hormones signal the plates to close.
• Litter position: Runts of the litter often catch up after weaning with proper nutrition, but may still be slightly smaller than littermates at maturity.
• Health: Parasites, illness, and nutritional deficiencies early in life can affect growth trajectories.

For a related tool, see our pet age calculator to convert your dog's age to human years and identify their current life stage. You can also explore more calculators in the Lifestyle & Entertainment section.

Puppy Nutrition and Growth — How Feeding Affects Adult Size

Diet during the first year of life has a significant impact on how a puppy grows — not by changing its genetic potential, but by determining whether that potential is fully realized. Key nutritional principles for healthy growth:

• Feed a life-stage-appropriate food — puppy foods are calorie-dense and higher in protein than adult formulas, supporting rapid growth. Large-breed puppy formulas are specially formulated to slow growth rate slightly — preventing the too-fast growth that can cause orthopedic problems in giant breeds.
• Avoid overfeeding — excess calories in growing puppies cause fat deposition that stresses developing joints. This is especially important for large and giant breeds where joint problems (hip dysplasia, elbow dysplasia) are common. Body condition score — feeling the ribs easily but not seeing them — is a better guide than a scale.
• Calcium and phosphorus balance — critical for bone formation. Do not supplement calcium in puppies fed a complete commercial puppy food. Excess calcium in large breeds can cause developmental bone disease.
• Avoid adult food too early — transition to adult food based on the breed size category: toy/small breeds at 9–12 months, medium breeds at 12–14 months, large breeds at 12–18 months, giant breeds at 18–24 months.

How to Tell If Your Puppy Is Overweight or Underweight

The scale alone does not tell the full story — body condition score (BCS) is more useful than raw weight for assessing a growing puppy:

• Ideal (BCS 4–5 on a 9-point scale) — ribs easily felt but not visible; waist visible when viewed from above; minimal tummy tuck seen from the side. This is the target for growing puppies.
• Underweight (BCS 1–3) — ribs, spine, or hip bones visible without pressing. Can indicate parasites, illness, poor-quality food, or insufficient feeding. Vet evaluation needed if persistent.
• Overweight (BCS 6–9) — ribs felt only with firm pressure; no visible waist; fat deposits over hips and base of tail. Reduce food quantity by 10–20% and recheck in 4 weeks. Avoid high-calorie treats.

Puppies naturally look slightly chubby at 8–12 weeks and then thin out as they grow taller before filling in at adult size. A brief "gangly" phase in adolescence (4–9 months) is normal. Compare weight to the breed weight chart for the puppy's age, not just adult expectations.

Mixed Breed Puppy Weight Prediction

Predicting the adult weight of a mixed-breed puppy is harder because the growth rate and maturity timeline depend on which breeds are in the mix. The best approach:

• Use a DNA breed test (like Embark or Wisdom Panel) to identify breed composition, then weight your estimate based on the dominant breeds' typical sizes.
• If you know the parents, average their weights as the baseline.
• Use the paw size as a rough indicator — larger paws relative to body size often (but not always) signal the puppy will grow into a larger adult.
• Weight at 16 weeks is often a good midpoint: for many medium mixed breeds, the adult weight is roughly 2× the 16-week weight.