Puppy Adult Weight Predictor
Predict how big your puppy will grow from its current weight and age, adjusted for expected adult size group.
Predictions get much more accurate after four months.
Based on the breed, or on the parents if it is a mix.
Predicted adult weight
22.6 kg
Likely range 20.4 to 24.9 kg. Individual dogs vary by roughly 10% either side even within a breed.
- Growth complete
- 53%
- Still to gain
- 10.6 kg
- Fully grown at about
- 12 months
- Months of growing left
- 8
Under four months this is a rough guide only. Puppies grow in bursts, so a single weigh-in taken during or just after a spurt skews the prediction. Weigh monthly and watch the trend rather than trusting one number.
How this is calculated
Puppies of a given size group reach a fairly predictable fraction of their adult weight at each age. Working backwards from that fraction gives an adult estimate.
adult weight = current weight ÷ (percentage grown ÷ 100) Worked example
A medium-breed puppy weighing 12 kg at four months is about 53% grown. Adult weight = 12 ÷ 0.53 = 22.6 kg, with a likely range of 20.3 to 24.9 kg.
Percentage of adult weight by age
| Age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 2 months | 28% | 24% | 20% | 17% |
| 3 months | 45% | 40% | 34% | 28% |
| 4 months | 60% | 53% | 46% | 38% |
| 6 months | 82% | 73% | 65% | 55% |
| 8 months | 92% | 86% | 78% | 68% |
| 10 months | 97% | 94% | 88% | 79% |
| 12 months | 100% | 100% | 95% | 87% |
| 18 months | — | — | 100% | 99% |
| 24 months | — | — | — | 100% |
A dash means the curve for that size group has already finished. Small breeds reach 100% at 12 months; giant breeds are still filling out at two years.
Sources
- WSAVA Global Nutrition Committee. Global Nutrition Guidelines and toolkit.
- American Animal Hospital Association. 2019 AAHA Canine Life Stage Guidelines.
- The percentage-of-adult-weight curves are the growth pattern described for each size group in veterinary pediatric nutrition references. They describe a typical shape, not a breed standard.
Growing at the right speed matters more than the final number
In large and giant breeds, growing too fast is a documented risk factor for developmental orthopaedic disease. The adult size is genetically set; overfeeding does not make a dog bigger, it makes it reach that size sooner and with worse joints. Feeding to the lean end of the range is the protective choice.
Weigh monthly and plot the trend with the growth chart calculator. A single weight is a data point; a curve is information.
Common questions
How big will my puppy get?
Divide current weight by the fraction of adult weight typical for its age and size group. A medium-breed puppy at four months is about 53% grown, so a 12 kg puppy should reach roughly 22.6 kg.
When is a puppy fully grown?
Small breeds finish around 12 months, medium around 12 to 14, large around 18, and giant breeds not until 24 months. This is why large-breed puppy foods exist and why joint-heavy exercise should wait.
How accurate is a puppy weight prediction?
It improves sharply with age. At eight weeks it is a rough guide with a wide margin. By six months it is usually within about 10%. Mixed breeds are harder than purebreds because the adult size group itself is a guess.
Can I predict adult size from paw size?
Not reliably. Large paws on a puppy are suggestive but not predictive, and plenty of dogs grow into normally proportioned adults from apparently oversized feet. Weight against age is a far better signal.
My puppy is much heavier than predicted. Is that a problem?
In large and giant breeds it can be. Growing too fast raises the risk of developmental orthopaedic disease including hip dysplasia and osteochondrosis. The fix is to feed to the lean end of the range rather than free-feeding. Discuss it with your vet before cutting food substantially.
How do I estimate the adult size group for a mixed breed?
Use the parents if you know them; a puppy usually lands between them. Otherwise a DNA test gives a reasonable estimate, and your vet can judge from frame, paw size and growth plates.