A dog size chart sorts dogs into classes by adult weight, and this one uses five: toy under 11 lb (5 kg), small 11–24 lb (5–11 kg), medium 24–51 lb (11–23 kg), large 51–90 lb (23–41 kg) and giant over 90 lb (41 kg). The classes matter for more than gear sizes, because how fast a puppy grows depends far more on how big it will end up than on which breed it is: dogs heading for the same adult weight follow much the same curve. Pick the class your puppy is growing into, or use the puppy weight calculator if you are not sure which one that is.
- Toy breedsUnder 11 lb (5 kg)7 charts
- Small breeds11-24 lb (5-11 kg)13 charts
- Medium breeds24-51 lb (11-23 kg)8 charts
- Large breeds51-90 lb (23-41 kg)10 charts
- Giant breedsOver 90 lb (41 kg)7 charts
Dog size chart by weight
The dog size chart below gives each class its adult weight range, the breeds this site has charted in it, and the age at which that class usually finishes growing. The weight boundaries are the ones every chart on this site uses; the finishing ages are where the median growth curve for the class reaches 95% of adult weight, taken from the same veterinary growth data as the charts and set out in full on when do dogs stop growing.
Boundaries between classes are by adult weight alone, not height or breed group, and a breed is placed by the midpoint of its adult range across both sexes. A Siberian Husky male stands at 45.0–60.0 lb under the standard and a female at 35.0–50.0 lb; the midpoint of that whole span is 47.5 lb, so the breed is medium here even though a big male crosses the 51 lb line. An Australian Shepherd male is 50.0–65.0 lb and a female 40.0–55.0 lb; the midpoint is 52.5 lb, so the breed is large. Other size charts draw the lines elsewhere and some use three or four classes rather than five; the figures are only comparable within one chart.
Which size class is a puppy in?
A puppy’s size class is the class of the adult weight it is heading for, not of its weight today. If you know the breed, the answer is on its breed weight chart, which states the class at the top of the page. If you do not, the current weight and age together usually settle it, because each class has reached a known share of adult weight at each age.
At 4 months, for example, a toy puppy is at about 61% of its adult weight on the median curve, a small puppy 59%, medium 56%, large 51% and giant 45%. A 4-month-old at 12 lb is therefore heading for about 20 lb whichever of the nearby classes you assume, which is small on this chart, and a 4-month-old at 30 lb for roughly 54 to 67 lb, which is large. The puppy weight calculator does this arithmetic with the full curves and returns a range rather than a point; the shares for other ages are in its table.
Puppies close to a boundary can read as either class for a few months, and a puppy that is unusually light or heavy for its class will be placed in the neighbouring one by weight alone. Neither is a fault in the puppy. Weigh again a month later and see which class the new figure agrees with.
Breed weight charts by size class
Breed weight charts sit under the size class each breed belongs to. Each one scales that class’s curve to the breed’s adult standard and splits it by sex, so a breed chart is always narrower than the class chart above it.
Toy breeds
Small breeds
Medium breeds
Large breeds
Giant breeds
When to use a breed chart instead
Use a size class chart when you do not know the breed — a mixed breed, a rescue of uncertain parentage, or a breed that does not have its own page here yet. The class chart has to cover every breed in that class at once, so its range is wide by design.
Use a breed weight chart when you do know. A breed page takes the same curve and scales it to that breed’s adult weight range from the American Kennel Club standard, then splits it by sex. That usually halves the range, which is the difference between a chart you can act on and one that only tells you the obvious.
The two are the same underlying data cut two ways, not competing answers. If a breed page and a class chart disagree, the breed page is the more specific of the two.
Why size class and not breed
The growth curves behind every chart here come from a study of around 15 million bodyweight records collected at US veterinary hospitals. Its central finding was that adult size, not breed, determines the shape of the growth curve: a 30 kg dog of any breed follows roughly the same trajectory. That is what makes one set of five curves able to serve every breed, and what makes an estimate possible for a puppy whose breed nobody knows.
Two honest caveats. The source records contain no breeds averaging between 14 and 23 kg, so the medium-class curve is interpolated from the classes either side and is the least certain of the five. And the original study could not model dogs above 40 kg, so the giant-class figures are percentiles calculated from the same raw records rather than results the study itself certified.
How to read any of these charts
Every row shows a range, not a target. A quarter of perfectly healthy puppies sit below the range for their age and a quarter above. What matters is the line your puppy holds across several weighings, not whether any single weigh-in lands inside the band. A puppy that has dropped from one part of the range to a lower one is worth a vet visit; a puppy that has always sat at the lighter end is usually just a lighter dog.
Frequently asked questions
How many dog size categories are there?
This dog size chart uses five: toy, small, medium, large and giant. Other charts use three or four, and the weight at which one class becomes the next differs from chart to chart, so a breed can be ‘medium’ on one chart and ‘large’ on another. On this site the boundaries are 5, 11, 23 and 41 kg of adult weight (11, 24, 51 and 90 lb), chosen so that each class has its own growth curve.
What weight is a medium-sized dog?
On this chart a medium dog weighs 24 to 51 lb (11 to 23 kg) as an adult. A Border Collie or a Siberian Husky falls in this class. The medium-class growth curve is the least certain of the five, because the source records contain no breeds averaging between 14 and 23 kg and the curve is interpolated from the classes either side.
Is a 30 lb dog small or medium?
A 30 lb adult dog is medium on this chart, which runs 24 to 51 lb. Breeds, though, are placed by the midpoint of their whole adult range rather than by any one dog, so a Pembroke Welsh Corgi is small on this chart at an adult 22.0 to 26.5 lb. A Border Collie is medium at an adult 30.0 to 55.0 lb. For a mixed breed of unknown parentage at 30 lb fully grown, use the medium chart and expect the light end of its range.
Does the dog size chart use height?
No. The five classes here are defined by adult weight only, because the growth curves behind every chart on this site are bodyweight curves and the source study found that adult weight, not breed or height, determines how a puppy grows. Height standards exist for most breeds in the American Kennel Club breed standards, but they are not used to place a breed in a class here.