Boston Terrier Weight Chart & Growth Guide
Updated · By the PetNoter team
Adult Boston Terriers typically weigh 5.4–11 kg (12–25 lbs). The range is wide because the breed comes in three weight classes. Sex makes less difference than which class a dog falls into, so one range covers males and females. Most Boston Terriers reach their full adult size by 12–14 months.
Typical weight at each age for a Boston Terrier, from a two-month-old puppy to a fully grown adult — and how to tell which end of the range your dog belongs at.
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Boston Terrier Weight Chart by Age
Adult Boston Terriers typically weigh 5.4–11 kg (12–25 lbs). That is a wide range because the American Kennel Club standard splits the breed into three classes: under 15 lbs, 15 to under 20 lbs, and 20 to 25 lbs. A healthy 7 kg Boston and a healthy 11 kg Boston are simply different sizes of dog.
| Age | Weight |
|---|---|
| 2 months | 0.9–1.9 kg (2–4.2 lbs) |
| 3 months | 1.6–3.4 kg (3.6–7.5 lbs) |
| 4 months | 2.3–4.7 kg (5–10 lbs) |
| 6 months | 3.7–7.7 kg (8.1–17 lbs) |
| 9 months | 4.8–9.9 kg (10–22 lbs) |
| 12 months | 5.4–11 kg (12–25 lbs) |
| Adult | 5.4–11 kg (12–25 lbs) |
Puppy ages are estimates, worked out from the breed's published adult weight and a typical growth curve for small breeds, not from a measured age-by-age study. A puppy from small parents will usually track the low end throughout, and one from larger parents the high end.
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These ranges are typical values for the breed, not a diagnosis. Individual healthy weight depends on frame, build and health history — ask your vet about your own pet.
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About the Boston Terrier
The Boston Terrier was developed in Boston, Massachusetts, in the late 1800s from bulldog and terrier crosses. Its neat tuxedo markings and easygoing manner earned it the nickname “the American Gentleman”, and it remains a lively, affectionate companion that suits city living.
With a smooth, short coat, a Boston's body condition is easy to see. A healthy dog has a compact, square outline with a visible waist. A broad, flat back and no tuck behind the ribs usually mean it is carrying too much.
Weight matters especially because this is a short-nosed breed. Extra fat around the chest and throat makes breathing harder and heat harder to shed, and it adds load to knees that can be prone to patellar luxation.
Growth Milestones and Healthy Weight
- Expect a Boston Terrier to be around two-thirds of its adult weight by six months, and close to finished at about 12 to 14 months.
- Parent size is one of the best clues to which class a puppy will reach, so ask your breeder what both parents weigh.
- Weigh weekly as a puppy and monthly as an adult, and compare your dog against its own earlier weights rather than the whole range.
- Check condition by feel and sight: ribs easy to find under light pressure, a waist from above, and a tuck from the side.
- Measure meals and keep treats under 10% of daily calories.
- Exercise in the cool parts of the day and stop early in warm weather. Short-nosed dogs overheat quickly, and that can limit how much weight exercise alone will take off.
- Talk to your vet about noisy breathing, reduced stamina or fainting, especially if your dog has also gained weight.
Want to know why your Boston Terrier weighs what it does?
PetNoter AI reads your Boston Terrier's weight history, age and notes, answers your questions about food, weight and health, and tells you how urgent it is.
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Bruno weighed 21 kg at his last check on 2026-02-21. That's on the leaner side for an adult male Doberman, so ask your vet to check his body condition and set a daily calorie target.
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Frequently Asked Questions
Sources and further reading
Check these figures against the references below. Every pet is different, so ask your vet what is right for yours.
- American Kennel Club: dog breeds — Breed standards, including typical adult height and weight
- FCI: breed nomenclature — Official standards for every FCI-recognised breed
- The Royal Kennel Club: breed standards — UK breed standards
- WSAVA Global Nutrition Guidelines — Body condition scoring charts for dogs and cats
Next steps for your Boston Terrier
Track your Boston Terrier's weight in the free PetNoter app
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