Puppy Weight Calculator
Enter your puppy's weight and age — get the expected adult weight and a growth chart up to 18 months.
Puppies do not grow in a straight line. They gain weight fast in the first months and then slow down, and the curve depends on size: toy breeds reach half their adult weight at around 11 weeks and are fully grown by 8–10 months, while large breeds weigh about half their adult weight at five months and keep growing for 15–18 months or longer. The calculator uses a logistic growth curve — the model fitted to puppy growth by Hawthorne et al. (Journal of Nutrition, 2004) and by later studies of breeds of different sizes — and divides the current weight by the share of adult weight expected at that age.
If you do not know the adult size, the calculator picks the size group whose range matches its own estimate. For example, a 12 kg puppy at 16 weeks lands in the large group with an expected adult weight of about 33 kg, typical of a Labrador. The table shows where the curve expects your puppy at each age, so you can weigh it every few weeks and see whether it follows. Breed, sex, neutering and diet all shift the result, so treat it as an estimate, not a promise.
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How big will my puppy get?
Enter its current weight and age. The calculator divides the weight by the share of adult weight a puppy of that size usually has at that age. A 5 kg puppy at 16 weeks on the small-dog curve, for example, is expected to reach about 9 kg — roughly a beagle.
How accurate is the estimate?
It is an average for the size group. Individual dogs, breeds within a group, males and females differ, and the estimate is less reliable before 12 weeks, when growth is fastest. Weigh the puppy every 2–4 weeks: if it keeps following the same curve, the estimate becomes more trustworthy.
Why not just use "weight ÷ age in weeks × 52"?
That rule assumes a puppy grows at the same rate all year, which it does not. For a medium puppy of 15 kg at 26 weeks it gives 30 kg, while the growth curve, which accounts for slowing growth, gives about 21 kg. The rule overestimates more the older the puppy.
At what age do dogs stop growing?
Small and toy breeds reach adult weight by about 8–10 months, medium breeds around 12 months, large breeds at 15–18 months and giant breeds up to 18–24 months. The skeleton finishes before the dog fills out.
When is a puppy half its adult weight?
Research on puppy growth curves puts it at about 11 weeks for toy breeds such as the Papillon, about 15 weeks for small breeds, 18 for medium and about 23 weeks (just over five months) for large breeds.
Does the calculator work for mixed breeds?
Yes — that is what the automatic size detection is for. For mixes the estimate can be less certain, so it helps to know the parents' sizes and to choose the size group manually if they are known.
Does neutering affect adult weight?
Neutered dogs tend to gain weight more easily because their energy needs fall, so feeding usually needs adjusting afterwards. The growth curves describe healthy dogs kept in good body condition.
Can I enter weight in pounds?
Yes. Choose kg or lb next to the weight field; the result and the table use the same unit. Age can be entered in weeks or months.
What if my puppy is above or below the curve?
Small deviations are normal. A puppy that is consistently gaining much faster or slower than the curve, or looks too thin or too round, should be checked by a vet — body condition matters more than any number on a chart.
Why is the age limited to 8 weeks – 18 months?
Before 8 weeks puppies are still nursing and their growth varies a lot; after 18 months most dogs, except giant breeds, are at their adult weight and the curve no longer adds information.