What size harness for a French Bulldog?
Most adult French Bulldogs take a small or medium harness, but because the breed has a notably broad, deep chest relative to its size and a short neck, going by a general size chart alone often gets the fit wrong. Measuring your own dog's chest girth and neck, and checking against a specific harness's actual measurements rather than its size label, gives a far more reliable fit.
Why French Bulldogs are hard to size from a chart
This breed's proportions don't match the average dog a generic size chart is built around — a broad, barrel-shaped chest combined with a short neck and compact body means a harness sized correctly for chest girth can still be wrong around the neck, and vice versa.
Brands also vary in how generously they cut a 'small' or 'medium', so the same label can fit quite differently between two harnesses. Checking a specific product's own measurement guide, rather than trusting the size name alone, avoids much of this inconsistency.
How to measure your dog properly
Measure chest girth at the widest point, usually just behind the front legs, using a soft tape measure snug but not tight against the fur. Measure neck circumference at the point a collar would normally sit, again snug rather than tight.
Take both measurements with your dog standing normally rather than sitting or stretched, since posture can change the numbers slightly. If your dog's measurements fall between two sizes on a specific harness's chart, sizing up and adjusting the straps snugly usually gives a more comfortable, adjustable fit than sizing down.
Checking the fit once it's on
A well-fitted harness should let you fit two fingers snugly between the strap and your dog's body at the chest and around the neck opening, without being loose enough to twist round or tight enough to restrict movement or breathing.
Given how much breathing effort already goes into being a flat-faced breed, avoiding anything that adds pressure around the neck or restricts chest expansion matters more with a French Bulldog than with many other breeds, which is part of why a well-fitted harness is generally preferred over a collar for walking this breed.
Common questions
- Why does my French Bulldog's harness keep twisting round?
- This usually means the harness is too loose, often because the neck opening doesn't match the dog's short, thick neck even if the chest strap fits. Rechecking both measurements against the specific harness's own size chart usually solves it.
- Should I size up or down if my French Bulldog is between two sizes?
- Generally size up and adjust the straps snugly, rather than sizing down and risking a harness that's too tight, particularly given how much this breed's chest and neck shape can vary between individual dogs.
- Is a harness better than a collar for a French Bulldog?
- Many owners and trainers prefer a well-fitted harness for this breed, since it avoids putting pressure directly on the neck of a dog that already works harder to breathe than a longer-nosed breed. A collar can still be useful for ID tags.
- How do I know if a harness is too tight?
- You should be able to fit two fingers snugly under every strap without forcing them in. If your dog seems reluctant to move normally, is panting heavily at rest, or the harness leaves visible marks, it's too tight and needs adjusting or resizing.
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Written against guidance published by UK veterinary and welfare organisations. Always confirm specifics with your own vet.
Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.