Puppy Growth Calculator
Predict your puppy's adult weight using vet-validated growth curves — enter current age and weight
🐶 Puppy Growth Calculator
Enter your puppy’s current age and weight to predict their adult size
Not sure? 8 weeks = 2 months, 12 weeks = 3 months, 16 weeks = 4 months
How to Predict Your Puppy’s Adult Weight
Predicting adult weight is one of the most common questions new puppy owners have — especially if you adopted a mixed breed and aren’t sure what size to expect. This calculator uses veterinary growth curve data to give you the most accurate estimate possible.
The Formula Vets Use
The most reliable method is based on the fact that puppies reach a predictable percentage of their adult weight at each age. For example, a medium breed puppy is typically about 50% of their adult weight at 16 weeks. By dividing current weight by that percentage, we can estimate adult size.
Why Breed Size Matters More Than Breed
Growth rate is primarily determined by how large the dog will be as an adult — not by specific breed. A small mixed breed follows the same growth curve as a purebred Beagle. This is why selecting the right size category is the most important input.
When Do Puppies Stop Growing?
- Toy breeds (under 12 lbs) — fully grown by 9 to 10 months
- Small breeds (12 to 25 lbs) — fully grown by 10 to 12 months
- Medium breeds (25 to 50 lbs) — fully grown by 12 to 15 months
- Large breeds (50 to 100 lbs) — fully grown by 15 to 18 months
- Giant breeds (over 100 lbs) — fully grown by 18 to 24 months
Mixed Breed Puppies
For mixed breeds, choose the size category that best matches what you expect the adult dog to be. If you’re unsure, a DNA test can identify the breeds present and give you a better size estimate. Most vets can also assess body structure to predict adult size at the 8-week checkup.