Boston Terrier Size and Weight: How Big Do They Get?
Boston Terriers are small but sturdy: most adults weigh 12 to 25 pounds and stand about 15 to 17 inches tall at the shoulder. Here's the full Boston Terrier size and weight picture: adult size, how fast puppies grow, and what decides how big yours will get.
Full-Grown Boston Terrier Size and Average Weight
| Height | About 15–17 inches at the shoulder |
|---|---|
| Typical weight | 12–25 pounds |
| Breed-standard weight classes | Under 15 lb · 15 to under 20 lb · 20 to 25 lb |
| Maximum (standard) | 25 pounds |
Males are often slightly larger than females, but there's a lot of overlap. A Boston's build matters as much as the scale: they should look square and muscular, not chunky.
Boston Terrier Puppy Growth Chart
Use this as a rough guide only. Puppies from smaller parents sit at the low end and puppies from larger parents at the high end.
| Age | Approximate weight |
|---|---|
| 8 weeks | 3–6 lb |
| 3 months | 5–9 lb |
| 4 months | 7–12 lb |
| 6 months | 10–17 lb |
| 9 months | 12–22 lb |
| 12 months | 12–25 lb |
When Do Boston Terriers Stop Growing?
Most Bostons reach their adult height by about 9 to 12 months and may fill out a little more over the following months. Growth is fastest in the first four to six months, so measured meals of a good puppy food matter most then.
How to Estimate Your Puppy's Adult Size
The parents are the best predictor. A puppy whose parents are both in the middle weight class will most likely end up there too, though nobody can promise an exact adult weight. That's why we show the parents of every litter on our parents page. Paw size and "doubling" formulas are much less reliable.
How Much Should a Boston Terrier Weigh?
You should be able to feel your Boston's ribs easily and see a waist when looking down from above. Extra weight makes breathing harder for a short-nosed dog and adds stress to the knees, so measure meals and count treats. Read more in our lifespan and health guide.
Large, Fat or Overweight Boston Terriers
A Boston over 25 pounds is either larger than the breed standard or carrying extra weight. Size above the standard isn't a health problem in itself. Extra fat is, because it makes breathing harder, strains the knees and shortens life. If your Boston looks round from above or you can't feel their ribs, cut portions a little and ask your vet for a target weight. Our Boston Terrier food guide explains how much to feed.
Boston Terrier Size Compared to Similar Breeds
| Breed | Height | Weight |
|---|---|---|
| Boston Terrier | 15–17 in | Up to 25 lb |
| French Bulldog | 11–13 in | Under 28 lb |
| Pug | 10–13 in | 14–18 lb |
See the full Boston Terrier vs French Bulldog comparison, or read about mini Boston Terriers if you want a smaller dog.
Boston Terrier Size FAQ
How big do Boston Terriers get?
Most adults weigh 12 to 25 pounds and stand about 15 to 17 inches tall at the shoulder. The breed standard caps weight at 25 pounds.
When do Boston Terriers stop growing?
Most reach their adult height by about 9 to 12 months old and may fill out a little more over the next few months.
Are there big Boston Terriers?
Some Bostons grow larger than 25 pounds, but that's above the breed standard. A very large "Boston" may also be overweight or a mix, so check the parents.
Looking for a Boston Terrier puppy? We have 32 puppies available in Worcester, Massachusetts.