French Bulldog vs Boston Terrier: How to Tell Them Apart and Which Suits You

French Bulldogs and Boston Terriers get mistaken for each other constantly, and with good reason: both are small, flat-faced, bat-eared companion dogs with short coats and short tails. If you’re choosing between them, there are a few real differences, and one of them matters more than the rest.

At a glance

	French Bulldog	Boston Terrier
Weight (breed standard)	Not over 28 pounds	Three classes: under 15 lb, 15 to under 20 lb, 20 to 25 lb
Build	Heavier boned, stockier	Lighter, longer in the leg
Standard colors	Brindle, fawn, white and combinations	Brindle, seal or black, always with white markings
Tail	Naturally short, straight or screwed	Naturally short; a docked tail is a disqualification
Free of BOAS signs	10%	37.5%

Sources: the French Bulldog and Boston Terrier breed standards, and Tomlinson and colleagues, 2024.

Size and build

A Boston Terrier is the lighter dog. The standard divides them into weight classes: under 15 pounds, 15 to under 20, and 20 to not more than 25. A French Bulldog can weigh up to 28 pounds and carries heavier bone, so even a similar-weight Frenchie feels more solid.

Neither standard sets a height, so treat the height figures you’ll see quoted online as rough.

The easiest way to tell them apart in person: the Boston looks like it’s wearing a tuxedo and has longer legs and a more delicate frame; the Frenchie is thicker through the chest with heavier bone.

Color

Both breeds’ standards are narrower than the market suggests.

Boston Terrier: brindle, seal or black, always with white markings. Anything else, including red, brown, blue, champagne and lilac, is outside the standard, and a solid dog without the required white markings is a disqualification. So are blue eyes and a Dudley (unpigmented) nose.

French Bulldog: white, cream and fawn with brindle, piebald, black masks and white markings. Blue, lilac, merle, black and tan, and chocolate are disqualifications, however they’re advertised. Our colors guide covers why that matters beyond the show ring.

Tails

Neither breed’s tail is docked. Both are naturally short, and it isn’t because tails were being injured in fights, which is the story you’ll often read. The screw tail traces to a variant in the DVL2 gene, found in every Bulldog and French Bulldog tested and in almost all Boston Terriers (Mansour and colleagues, 2018).

That variant is also associated with malformed vertebrae further up the spine, so both breeds see hemivertebrae. In French Bulldogs, 90% to 100% of dogs examined had at least one abnormal vertebra (UFAW). Most never show signs; when they do, it’s usually before seven months. Our tail guide covers it.

For a Boston, a docked tail is a disqualification.

The difference that matters: breathing

Both are brachycephalic, but they are not equally affected. In a study comparing screw-tailed breeds, 37.5% of Boston Terriers scored BOAS grade 0, meaning free of respiratory signs, against 10% of French Bulldogs and 15.2% of Bulldogs. The authors concluded Boston Terriers “appear to be less severely affected by BOAS than the most popular extreme brachycephalic screw-tailed breeds” (Tomlinson and colleagues, 2024).

That’s a meaningful difference if you want a dog who copes better with exercise and warm weather. It is not a clean bill of health: Bostons are still flat-faced, and within the breed, a shorter muzzle still raised BOAS risk in the same study. Our health issues guide covers what to look for in either breed.

Other health differences

Eyes. Both have prominent eyes in shallow sockets, and flat-faced breeds have over 11 times the risk of corneal ulcers compared with other dogs (RVC VetCompass). Boston Terriers are particularly known for eye problems, including cataracts and corneal ulcers. Squinting, pawing at the face, redness or cloudiness in either breed is a same-day vet visit.

Skin folds. Frenchies have deeper facial folds and need them cleaned and dried regularly. Bostons have far less of this.

Kneecaps and spine. Both breeds see luxating patella and spinal problems.

Birth. Both are usually delivered by caesarean, which is part of why both are expensive to buy.

Whichever you choose, pet insurance is worth arranging early.

Temperament and energy

Both are companion breeds that want to be with people, and neither is a guard dog.

The Boston is the busier of the two: moderate energy, quick, playful, and often described as more biddable in training. The Frenchie is typically calmer indoors, more of a lap dog, and more single-minded when they don’t see the point of something.

Neither needs much exercise, and both need some. Short walks in the cool part of the day plus indoor play suits both; our guide to walking a French Bulldog applies to a Boston too, with a little more scope given the better breathing.

Training

You’ll read that a French Bulldog needs “more authority”. It doesn’t. Both breeds do best with short, reward-based sessions, and methods relying on force or intimidation are the ones that cause problems (AVSAB).

The real difference is motivation, not obedience: Bostons tend to offer behavior readily, while Frenchies want to know what’s in it for them. Our training guide and our guide to stubbornness cover it.

Grooming

Near-identical: short coats, weekly brushing with a slicker brush, nails, ears, and a bath when they need one rather than on a schedule. Our bathing guide covers how often, and the Frenchie’s folds need the extra attention.

Living space

Both suit apartments, and both need a home that stays cool in summer. Neither should live outdoors.

Which should you choose?

Choose a Boston Terrier if you want a slightly more active dog who is likely to breathe more easily and cope better with warmth, and if the tuxedo look appeals.

Choose a French Bulldog if you want a heavier, calmer companion who is content to be a lap dog, and you can manage the folds, the heat and the higher likelihood of breathing problems.

For either, the breeder matters more than the breed. Ask about BOAS grading and health testing, watch how the parents breathe at rest, and favor moderate faces over extreme ones. Our breeder questions guide covers what to ask, and both breeds turn up in rescue.