“How big will my puppy get?” is one of the first questions new owners ask. You can make a reasonable guess from today’s weight, age, and the size group your puppy is likely to end up in. The calculator below uses published growth standard charts built from the weight records of pet dogs, and shows a range rather than one number, because individual puppies grow differently.
Free calculator
Puppy weight calculator
- Share of 2-year weight now
- about 31%
A rough range from population growth charts, not a prediction for your puppy. The parents’ size and your vet’s growth checks are better guides.
How the estimate works
In 2017, researchers led by the WALTHAM Petcare Science Institute published growth standard charts for dogs in five size groups, from under 6.5 kg (14 lb) to 40 kg (88 lb) as adults. The charts show how weight typically rises from 12 weeks to 2 years of age.
We read the middle (50th centile) curve for each size group and expressed each age as a share of the typical weight at 2 years. If a medium-size puppy weighs 12 lb at 12 weeks and puppies that size are usually about 31% of their 2-year weight at that age, the estimate lands around 35–43 lb. The range reflects the difference between the female and male curves plus a margin for reading the charts.
Puppy growth chart: share of 2-year weight by age
Average of the female and male median curves, read from the published charts. Treat these as approximate.
| Adult size | 12 wk | 16 wk | 20 wk | 6 mo | 9 mo | 12 mo | 18 mo | 2 yr |
|---|---|---|---|---|---|---|---|---|
| Toy (adult under 14 lb / 6.5 kg) | 38% | 48% | 57% | 67% | 80% | 86% | 94% | 100% |
| Small (adult 14–20 lb / 6.5–9 kg) | 36% | 48% | 59% | 70% | 84% | 89% | 96% | 100% |
| Medium (adult 20–33 lb / 9–15 kg) | 31% | 43% | 53% | 65% | 81% | 88% | 95% | 100% |
| Large (adult 33–66 lb / 15–30 kg) | 30% | 42% | 55% | 70% | 88% | 94% | 98% | 100% |
| Very large (adult 66–88 lb / 30–40 kg) | 29% | 42% | 54% | 70% | 88% | 94% | 97% | 100% |
Two patterns stand out. In every size group, puppies reach just over half of their 2-year weight by about 20 weeks. And in these charts, many dogs keep gaining slowly well into their second year, so a 12-month-old is often not quite at full adult weight.
What this calculator cannot tell you
- Giant breeds. The charts do not cover dogs heavier than 40 kg (88 lb) as adults, such as Great Danes or Mastiffs, because their growth varies widely. The calculator does not estimate them.
- Mixed-breed guesses. If you are unsure which size group your puppy belongs to, try two neighboring groups and treat the overlap as the most likely range.
- Individual health. Illness and diet can shift growth. A puppy dropping across the growth curves, or climbing much faster than expected, is worth showing to a veterinarian.
Track growth, not just one number
The original charts were built so veterinarians could plot a puppy’s weights over time and spot unusual growth early. You can help by weighing your puppy regularly, under similar conditions, and bringing the dated record to vaccine and wellness visits. Our weight-tracking guide explains how to make each reading comparable, and the dog calorie calculator estimates how much a growing puppy needs to eat.
Pup AI keeps every weigh-in on a timeline with the meals, activity, and vaccine dates around it, so the growth story is in one place when the veterinary team asks how your puppy has been doing.