Puppy Weight Calculator
Estimate how big your puppy will be as an adult. Enter its age and current weight, pick the expected breed size, and get an adult weight estimate with a likely range, milestones at 6 months and 1 year, and a full growth chart.
At least 8 weeks.
How to use the Puppy Weight Calculator
- Choose your units for weight (lb or kg) and age (weeks or months).
- Enter your puppy's age (at least 8 weeks) and its current weight from a recent weigh-in.
- Pick the breed size your dog is expected to be as an adult. For mixed breeds, go by the parents' size.
- Press Estimate adult weight to see the estimate, likely range and growth milestones.
- Check the growth table and weigh your puppy every few weeks to see whether it is tracking the curve.
How the estimate works
Estimated adult weight = current weight ÷ share of adult weight reached at this age
The share comes from a growth curve for the chosen size class. Between the listed ages the calculator interpolates in a straight line. Example: a large-breed puppy at 12 weeks has reached about 29% of its adult weight, so a 25 lb puppy is on track for about 25 ÷ 0.29 ≈ 86 lb.
Typical share of adult weight by age
| Age | Toy | Small | Medium | Large | Giant |
|---|---|---|---|---|---|
| 8 weeks | 33% | 28% | 22% | 17% | 13% |
| 12 weeks | 52% | 45% | 36% | 29% | 23% |
| 16 weeks | 68% | 60% | 50% | 41% | 33% |
| 20 weeks | 80% | 72% | 62% | 52% | 43% |
| 6 months | 90% | 85% | 75% | 65% | 55% |
| 9 months | 97% | 95% | 89% | 81% | 71% |
| 12 months | 100% | 100% | 98% | 93% | 86% |
| 18 months | 100% | 100% | 100% | 100% | 97% |
These percentages are approximate averages consistent with published growth studies of pet dogs, which show that smaller breeds mature faster than larger ones. Individual puppies can be ahead of or behind the curve.
Adult size classes
- Toy: up to about 12 lb (5.4 kg)
- Small: 12 to 25 lb (5.4 to 11.3 kg)
- Medium: 25 to 50 lb (11.3 to 22.7 kg)
- Large: 50 to 100 lb (22.7 to 45 kg)
- Giant: over 100 lb (45 kg)
Frequently asked questions
How do you calculate a puppy's adult weight?
Puppies of the same size class grow along a fairly predictable curve. The calculator looks up what share of adult weight a typical puppy of that size has reached at the current age, then divides the current weight by it. For example, a medium-breed puppy at 16 weeks is about 50% grown, so a 15 lb puppy should end up near 30 lb.
How accurate is a puppy weight calculator?
It gives a reasonable estimate, usually within about 15% for purebred dogs, which is why a range is shown. Genetics, neutering age, diet and the size of the parents all matter, and mixed breeds are harder to predict. Estimates get more reliable as the puppy gets older.
When do puppies stop growing?
Toy and small breeds usually reach adult weight at about 9 to 12 months, medium breeds at about 12 to 15 months, large breeds at 15 to 18 months and giant breeds at 18 to 24 months. Height growth generally finishes before the dog fills out.
Is there a quick rule of thumb?
A common rule is that many medium and large dogs reach about half their adult weight around 4 to 5 months, so doubling the weight at that age gives a rough guess. Small breeds get there sooner and giant breeds later, which is why this calculator uses a separate curve for each size.
Can paw size predict how big my puppy will get?
Large paws relative to the legs can hint that a puppy has more growing to do, but paw size is not a reliable predictor. Current weight, age and the parents' size are much better guides.
My puppy is above or below the estimate. Should I worry?
Not necessarily, because individual dogs vary. Use body condition (you should feel the ribs easily under a thin layer of fat) rather than the number alone, and ask your vet if your puppy seems too thin, overweight or is growing unevenly.