Boston Terrier Weight Chart by Age

An adult Boston Terrier weighs 12.0–25.0 lb (5.4–11.3 kg), according to the American Kennel Club breed standard, which gives one range for both sexes.

A male is typically 5.5–11.4 lb (2.5–5.2 kg) and a female 5.7–11.8 lb (2.6–5.4 kg) — around 46% of adult weight.

Roughly 7.0–14.6 lb for a male and 7.1–14.9 lb for a female, about 59% of the way to adult weight.

A male is usually 9.3–19.3 lb (4.2–8.8 kg) and a female 9.2–19.2 lb (4.2–8.7 kg).

11.1–23.1 lb for males and 11.1–23.1 lb for females — about 93% of final weight, with the rest filling in over the following months.

At 59% of adult weight by 4 months, a rough shortcut is to double a four-month weight. The calculator on the home page does this properly, using the growth curve for this size class and returning a range rather than one number.

Height is usually settled first; weight keeps filling in until around 12 months. The last 7% of adult weight takes roughly as long as the jump from 3 to 4 months.

The AKC standard gives the same three weight classes for both sexes, under 15 lb, 15 to 20 lb and 20 to 25 lb, so the chart columns are the same. Males in most breeds finish a little heavier than females, but in a breed bred in three sizes the class a dog belongs to matters far more than its sex. Expect a female to sit slightly lower on the chart than a male of the same class, and do not read that as underweight.

A small breed, defined by adult weight. That classification determines the growth curve used here: veterinary research shows dogs of similar adult size grow at similar rates regardless of breed.

Not necessarily. The table shows the middle of the healthy range, so plenty of healthy puppies sit below it. A puppy that is consistently below and not gaining, or that has dropped from a higher line to a lower one, is worth a vet visit. A single reading below the range is not.

Body condition tells you more than the scale. You should be able to feel the ribs under a thin layer of fat without pressing, see a waist from above, and see the belly tuck up from the side. A dog can sit inside the weight range and still carry too much fat.

Most published charts come from one breeder’s litters or from unsourced rules of thumb, and many do not say whether the figures are for males, females or both. The ranges here come from centile curves fitted to millions of veterinary bodyweight records, scaled to the AKC adult range, and split by sex.

The research behind these curves found neutering shifted growth trajectory only slightly, by less than the variation between individual dogs, so separate curves were not needed. Neutering is associated with a higher chance of becoming overweight in adulthood, which is a body condition question rather than a growth chart one.

An adult Boston Terrier weighs 5.4–11.3 kg for both sexes under the American Kennel Club standard. On the median growth curve a male is 2.5–5.2 kg at 3 months, 4.2–8.8 kg at 6 months and 5.0–10.5 kg at 12 months; a female 2.6–5.4 kg, 4.2–8.7 kg and 5.0–10.5 kg. Every row of the chart above gives kilograms under the pounds.

The American Kennel Club standard gives one range for both sexes, 12.0–25.0 lb (5.4–11.3 kg); it does not publish a separate female figure. On the female growth curve a female Boston Terrier is about 7.1–14.9 lb at 4 months, 9.2–19.2 lb at 6 months and 11.1–23.1 lb at 12 months, reaching adult weight at around 12 months. The Female column of the chart above gives every month.

The American Kennel Club standard gives one range for both sexes, 12.0–25.0 lb (5.4–11.3 kg); it does not publish a separate male figure. On the male growth curve a male Boston Terrier is about 7.0–14.6 lb at 4 months, 9.3–19.3 lb at 6 months and 11.1–23.1 lb at 12 months, reaching adult weight at around 12 months. The Male column of the chart above gives every month.