Dog Size Calculator
Predict your puppy's adult weight and size category. Enter your puppy's current age and weight to estimate how big they'll grow.
How We Calculate Adult Dog Weight
The Formula
This formula estimates adult weight by calculating the weekly growth rate and projecting it over a full year (52 weeks).
Example Calculation
A puppy weighing 4 kg at 12 weeks:
Adult Weight = (4 ÷ 12) × 52 = 17.3 kg (approximately 38 lbs)
Dog Size Categories
Toy
Mature at: 8-10 monthsWeight: < 5 kg (11 lbs)
Height: < 25 cm (10 in)
Examples: Chihuahua, Yorkshire Terrier, Pomeranian, Maltese
Small
Mature at: 10-12 monthsWeight: 5-10 kg (11-22 lbs)
Height: 25-40 cm (10-16 in)
Examples: French Bulldog, Beagle, Dachshund, Shih Tzu
Medium
Mature at: 12-15 monthsWeight: 10-25 kg (22-55 lbs)
Height: 40-55 cm (16-22 in)
Examples: Border Collie, Cocker Spaniel, Bulldog, Australian Shepherd
Large
Mature at: 15-18 monthsWeight: 25-45 kg (55-100 lbs)
Height: 55-70 cm (22-28 in)
Examples: Labrador Retriever, Golden Retriever, German Shepherd, Boxer
Giant
Mature at: 18-24 monthsWeight: > 45 kg (100 lbs)
Height: > 70 cm (28 in)
Examples: Great Dane, Saint Bernard, Mastiff, Newfoundland
Puppy Growth Milestones
| Age | % of Adult Size | What's Happening |
|---|---|---|
| 8 weeks | 20-25% | Puppy leaves breeder, rapid growth begins |
| 3-4 months | 40-50% | Teething begins, still growing rapidly |
| 6 months | 60-70% | Growth slows, adult teeth come in |
| 9-12 months | 80-90% | Small breeds near adult size |
| 12-18 months | 90-100% | Medium/large breeds reach adult size |
| 18-24 months | 100% | Giant breeds finish growing |
Important Notes
Estimation Accuracy
This calculator provides an estimate based on average growth patterns. Actual adult size can vary by 10-20% depending on breed, genetics, nutrition, and health factors. Mixed breed dogs may show more variation than purebreds.
Best Age for Prediction
The most accurate predictions are made when puppies are between 8-16 weeks old. Very young puppies (under 8 weeks) or older dogs may give less accurate results.
Growth Rate Variations
- • Toy/Small breeds: Reach adult size fastest (8-12 months)
- • Medium breeds: Mature around 12-15 months
- • Large breeds: Continue growing until 15-18 months
- • Giant breeds: May grow until 18-24 months
Frequently Asked Questions
How accurate is the dog size prediction?
The prediction is generally accurate within 10-20% for purebred dogs. Mixed breed puppies may vary more. The formula works best for puppies between 8-16 weeks old when growth patterns are most consistent.
When do dogs stop growing?
It depends on the breed size. Toy and small breeds typically reach adult size by 10-12 months. Medium breeds mature around 12-15 months. Large breeds take 15-18 months, and giant breeds like Great Danes may continue growing until 18-24 months.
Can nutrition affect my dog's adult size?
Yes, nutrition plays a crucial role. Proper nutrition supports healthy growth, while underfeeding can stunt growth and overfeeding can lead to obesity or orthopedic problems in large breed puppies. Always follow veterinary guidance for your puppy's diet.
Is paw size a good predictor of adult size?
Paw size can give a rough indication—puppies with larger paws often grow into bigger dogs. However, it's not a precise measurement. The weight-based formula provides a more reliable estimate of adult size.
Why does my puppy's predicted size seem too big/small?
Several factors can affect this: the puppy may be over or underweight for their age, they might be from particularly large or small parents, or they could be a mixed breed with unpredictable growth patterns. If concerned, consult your veterinarian.
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