Written by Muhammad Ahtisham, dog nutrition and feeding specialist. Last updated November 8, 2026.
How to use this calculator
- Enter your puppy's age in weeks or months.
- Enter the current weight in pounds or kilograms.
- Pick the expected adult size group.
- Press the button for a weight and a likely range.
How the puppy weight calculator works
Puppies follow a typical growth curve, and the curve depends on size. I use rounded points from typical puppy growth charts and fill in between them. Your puppy's weight divided by the share of adult weight usually reached at that age gives the estimate. The range is wider for young puppies, because early weights say less about the end result.
| Age | Toy or small | Medium | Large | Giant |
|---|---|---|---|---|
| 8 weeks | 28% | 22% | 18% | 15% |
| 16 weeks | 58% | 50% | 45% | 40% |
| 26 weeks | 83% | 74% | 68% | 62% |
| 40 weeks | 96% | 91% | 87% | 80% |
| 52 weeks | 100% | 98% | 95% | 88% |
Worked example
- A medium puppy weighs 13 lb at 16 weeks.
- At 16 weeks a medium puppy has reached about 50 percent of adult weight.
- 13 divided by 0.50 gives about 26 lb, with a likely range of about 23 to 29 lb.
What can throw it off
Mixed breeds, illness, worms, and overfeeding all change the result. Parents' weights are the best second clue. Read the adult weight guide for more.
When to talk to your vet first
Dogs with kidney disease, diabetes, pancreatitis, allergies, or any other health problem need a plan from a vet. Read the terms before you change your dog's routine.