Updated
Puppy weight calculator
How big will your puppy get? This estimate uses the percentage-of-adult-weight method behind the WALTHAM growth charts — at a known age a puppy of a given size class has reached a known share of its adult weight — rather than the "× 52" rule that pretends every dog is grown at a year. The answer is always a range, because that is what the method can honestly give.
20.9 lb, estimated adult weight
Likely range 17.9 lb to 24 lb (±15 %, the method’s error). Medium breeds are about half grown at four months and finish by about 14 months.
- Share of adult weight reached today
- 48 %
- Method
- Percentage of adult weight: at 16 weeks a medium-breed puppy is about 48 % grown, so adult weight ≈ current ÷ 0.48. The 50 % age (17 weeks) and maturity (14 months) are published; the curve between them is this site's interpolation.
- Published anchors for this size class
- Half of adult weight at 17 weeks; growth complete at about 14 months (Salt et al. 2017; WALTHAM)
- Better than any formula
- A breed-specific growth chart from your vet, or WALTHAM’s own charts, beats any formula.
What this means
A toy breed is close to full size at nine months; a giant breed is still growing at eighteen. The "× 52" formula ignores that, over-predicting small dogs and under-predicting large ones by the same mechanism. Percentage of adult weight, with size-specific anchors, is the method the growth-chart research uses.
Only two facts per size class are public: the age at which a puppy is half grown and the age at which growth is complete. The curve between them on this page is our interpolation through those points, and it is labelled as such; the ±15 % range is the price of that honesty.
The size class matters more than the breed name. Take it from the parents’ adult weights if you know them; for a mixed breed with unknown parents, a DNA test or the vet’s paw-and-frame judgement beats guessing.
Puppy size class by breed
Not sure which size to choose? The 40 most popular US breeds with a published adult weight, and the size class it puts them in. For a breed whose range crosses a boundary, try both classes. Weights are the breed standards (American Kennel Club where it gives one).
| Breed | Adult weight | Size class to choose |
|---|---|---|
| French Bulldog | 18–28 lb | Medium |
| Labrador Retriever | 55–80 lb | Large |
| Golden Retriever | 55–75 lb | Large |
| German Shepherd Dog | 50–90 lb | Large |
| Dachshund | 11–32 lb | Medium |
| Beagle | 13–30 lb | Medium |
| Rottweiler | 80–135 lb | Giant |
| Bulldog | 40–50 lb | Medium |
| German Shorthaired Pointer | 45–70 lb | Large |
| Yorkshire Terrier | 7 lb | Toy |
| Australian Shepherd | 40–65 lb | Large |
| Cavalier King Charles Spaniel | 13–18 lb | Small |
| Pembroke Welsh Corgi | 28–30 lb | Medium |
| Doberman Pinscher | 60–100 lb | Large |
| Boxer | 15–80 lb | Medium |
| Miniature Schnauzer | 11–20 lb | Small |
| Bernese Mountain Dog | 70–115 lb | Giant |
| Shih Tzu | 9–16 lb | Small |
| Great Dane | 110–175 lb | Giant |
| Pomeranian | 3–7 lb | Toy |
| Boston Terrier | 12–25 lb | Small |
| Miniature American Shepherd | 20–40 lb | Medium |
| Havanese | 7–13 lb | Small |
| Siberian Husky | 35–60 lb | Medium |
| Chihuahua | 6 lb | Toy |
| English Springer Spaniel | 40–50 lb | Medium |
| Shetland Sheepdog | 15–25 lb | Small |
| Border Collie | 30–55 lb | Medium |
| Brittany | 30–40 lb | Medium |
| Cocker Spaniel | 20–30 lb | Medium |
| Belgian Malinois | 40–80 lb | Large |
| Basset Hound | 40–65 lb | Large |
| Vizsla | 44–60 lb | Large |
| English Cocker Spaniel | 26–34 lb | Medium |
| Maltese | 7 lb | Toy |
| Pug | 14–18 lb | Small |
| Collie | 50–75 lb | Large |
| Mastiff | 120–230 lb | Giant |
| West Highland White Terrier | 15–20 lb | Small |
| Shiba Inu | 17–23 lb | Small |
When to see a vet
- A puppy that has not gained weight in two weeks, or has lost weight, at any age.
- A large or giant puppy growing faster than its breed chart: over-feeding in the growth phase is linked to joint disease, and the food amount should be set with the vet.
- Any puppy well outside the range for its expected size that is also lethargic, pot-bellied or off its food.
Formula and sources
Sources reviewed 18 September 2026. Each names the figure it supports.
- Half-weight ages and maturity ages by size class (the two anchors of the curve) — Salt C. et al., "Growth standard charts for monitoring bodyweight in dogs of different sizes", PLOS ONE 12(9), 2017
- Breed-size growth charts an owner can plot a puppy on directly — WALTHAM Petcare Science Institute, puppy growth charts
- Growth patterns by breed size behind the size classes — Hawthorne A. J. et al., "Body-weight changes during growth in puppies of different breeds", Journal of Nutrition 134(8), 2004
This page is an educational estimate, not veterinary advice.
Frequently asked questions
How big will my puppy get?
Divide the current weight by the share of adult weight a puppy of that size class has reached at that age. At 16 weeks a medium-breed puppy is a little under half grown, so a 10 lb puppy will be about 21 lb as an adult, with a likely range of 18 to 24 lb. That is what this puppy weight estimator does for you: it predicts adult weight from the puppy’s current weight, age and size class.
How accurate is a puppy weight calculator?
To within about 15 % for a puppy of known size class in the 8–26-week window, and less for large and giant breeds under 20 weeks. Breed-specific growth charts, which plot the puppy against thousands of others, are more accurate than any formula.
When do puppies stop growing?
Toy breeds at about 9 months, small at 10, medium at 14, large at 18 and giant breeds at about 24 months (Salt et al. 2017). Bones finish first; muscle and "filling out" continue for a few months after.
How do I use it for a mixed-breed puppy?
Choose the size class from the parents’ adult weights if you know them, or from the breeds in the mix using the table on this page. If the parents are different sizes, run the calculator with both classes: the two results bracket the likely adult weight.
Can I predict my puppy’s weight by breed?
Yes, through the size class: find the breed in the table on this page, choose its size class, then enter the puppy’s weight and age. The size class sets how grown the puppy is at each age, which is what turns today’s weight into an adult estimate.
Does the "× 52" formula work?
Only by accident for medium breeds. It takes the weight gained per week so far and multiplies by 52 weeks, which assumes every dog grows at the same rate until exactly one year. Three of the ten top-ranking tools use it, two while citing research that says otherwise.