PuppyGrowthHow the puppy weight calculator works
Puppies don't grow in a straight line. They grow fastest in the first few months and then slow down, and big breeds keep growing for much longer than small ones. A toy breed can be full grown at 9–10 months, while a Great Dane may keep filling out until 2 years.
So instead of the popular shortcut (weight ÷ age in weeks × 52), which overestimates many large breeds, PuppyGrowthCalc uses a separate growth curve for each size class. Each curve says roughly what share of its adult weight a puppy has reached at a given age. Your puppy's current weight is divided by that share to project its adult weight.
Typical share of adult weight by age
| Age | Toy | Small | Medium | Large | Giant |
|---|---|---|---|---|---|
| 2 months | 25% | 22% | 18% | 15% | 11% |
| 3 months | 40% | 36% | 30% | 25% | 19% |
| 4 months | 55% | 50% | 42% | 36% | 28% |
| 6 months | 78% | 72% | 62% | 55% | 45% |
| 8 months | 92% | 86% | 76% | 70% | 60% |
| 10 months | 100% | 95% | 87% | 82% | 72% |
| 12 months | 100% | 100% | 95% | 90% | 82% |
| 15 months | 100% | 100% | 100% | 97% | 91% |
| 18 months | 100% | 100% | 100% | 100% | 96% |
These curves are smoothed estimates built from published puppy growth milestones. Individual puppies can be 10–20% above or below and still be perfectly healthy.
Why weight alone isn't the whole story
Vets judge puppies by body condition too: you should be able to feel (but not see) the ribs, and see a waist from above. A puppy that is on the heavy side of the chart but lean and active is often just a big puppy. Rapid weight gain in large and giant breeds can strain developing joints, which is why these breeds usually eat a large-breed puppy food.
Frequently asked questions
How accurate is a puppy weight calculator?
It gives an estimate, usually within 10–20% for purebred puppies. Accuracy improves as your puppy gets older, so re-check every few weeks.
At what age do puppies reach half their adult weight?
Toy and small breeds reach about half their adult weight at 3–4 months, medium breeds around 5 months, and large and giant breeds around 6 months or later.
Can I use this calculator for a mixed breed?
Yes. Choose "Mixed breed" and pick the size you expect, for example based on the parents' size. The estimate is less precise than for a purebred.
Do paw size and parents predict adult size?
Big paws are only a loose hint. The parents' weights are the best clue for a mixed breed; growth curves are better for a purebred.
When do puppies stop growing?
Toy breeds around 9–10 months, small breeds 10–12 months, medium breeds 12–14 months, large breeds 15–18 months and giant breeds 18–24 months.
More free pet calculators
PuppyGrowthCalc gives general estimates for healthy pets. Every animal is different. Ask your vet about your pet's ideal weight, diet and health.