Updated November 2026 · Research-based guide · We may earn a commission from links on this page.
A harness that is too loose can slip off on a walk; one that is too tight rubs behind the legs and makes your dog miserable. The short answer: measure around the widest part of your dog’s chest, just behind the front legs, and pick the size whose chest girth range includes that number. Weight is only a rough guide. If you land between two sizes, check what that brand recommends, because brands disagree.
This dog harness size chart pulls together the measuring advice from the American Kennel Club (AKC) and VCA Animal Hospitals and the published size charts of four widely sold harnesses. Once you know your dog’s size, our guide to the best no-pull dog harnesses compares front-clip and dual-clip picks for dogs that pull.
How to measure your dog for a harness
- Chest girth (the number that matters most): with your dog standing, wrap a soft tape measure around the widest part of the rib cage, usually just behind the front legs. The AKC recommends measuring with your dog standing so their back is straight.
- Neck: measure around the base of the neck, where it meets the shoulders. Not every brand asks for it, but harnesses with a neck loop, such as Kurgo’s, list a neck range too.
- Leave finger room: the AKC’s gear-measuring guide suggests keeping two fingers between the tape and your dog while you measure, so the result isn’t too tight.
- Weigh your dog: some charts list weight. Use it to narrow the choice, then let the girth measurement decide.
Write down both numbers in inches. If your dog is very fluffy, keep the tape snug against the body rather than on top of the fur; 2 Hounds Design describes the right tension as “snug but not too tight.”
Dog harness size chart by girth and weight
Here is one manufacturer’s full chart, which lists girth, chest width and weight for each size. It is a useful starting point because it covers everything from toy breeds to giant dogs:
| Size | Chest girth (in) | Approx. weight |
|---|---|---|
| Petite | 12–17 | Under 10 lb |
| Petite/Small | 13–18 | 10–15 lb |
| Small | 15–21 | 15–25 lb |
| Small/Medium | 19–26 | 20–30 lb |
| Medium | 22–32 | 25–50 lb |
| Medium/Large | 24–34 | 40–65 lb |
| Large | 27–40 | 65–95 lb |
| Extra Large | 32–49 | 90 lb and up |
Notice how much the ranges overlap. A dog with a 25-inch chest could fit a Small/Medium, Medium or Medium/Large Easy Walk, depending on where the adjustment straps sit. That is why the measurement beats the weight column: two 40-pound dogs can have very different chests.
Same dog, different brand: how sizes compare
A “Medium” in one brand is not a “Medium” in another. These are the chest girth ranges each maker publishes for its own harness:
| Harness | Sizes and chest girth (inches) | Weight listed? |
|---|---|---|
| Ruffwear Front Range | XXS 13–17 · XS 17–22 · S 22–27 · M 27–32 · L/XL 32–42 | No, girth only |
| Kurgo Tru-Fit Smart | XS 12–18 · S 16–22 · M 18–28 · L 24–34 · XL 28–44 (neck ranges also listed) | Yes, 5 to 110 lb |
| 2 Hounds Design Freedom | XXS 13–16 · XS 14–20 · S 20–24 · M 24–28 · L 28–32 · XL 32–36 · XXL 36–44 | Yes, as a guideline |
| PetSafe Easy Walk | Petite 12–17 up to XL 32–49 (full chart above) | Yes, approximate |
For example, a dog with a 27-inch chest is at the top of Ruffwear’s Small and the bottom of its Medium, inside both Kurgo’s Medium and Large, and in 2 Hounds’ Medium. Always use the chart for the exact harness you are buying.
What if your dog is between sizes?
This is where brands give opposite advice:
- Size up: PetSafe says to choose a size up for the Easy Walk, and Ruffwear says to choose the larger size for the Front Range. A larger harness has more room to tighten the straps.
- Size down: 2 Hounds Design recommends the smallest size that still fits for its Freedom harness.
- No advice: Kurgo’s Tru-Fit page doesn’t say; its size ranges overlap heavily, so most dogs fall inside two sizes.
Follow the maker of the harness you buy. If the brand says nothing, pick the size that puts your dog’s girth closest to the middle of the range, so you can adjust in either direction. The AKC also suggests looking for adjustable designs if your dog is between sizes.
Sizing a harness for a puppy
The AKC calls harnesses a good option for puppies, as long as you keep adjusting the size as they grow. Plan to re-measure often. 2 Hounds Design suggests checking the fit every few weeks and notes that large breeds can take 12 to 24 months to reach their adult size.
- Choose a harness with several adjustment points so it can grow with your puppy for a while.
- Buy for the puppy you have now, not the adult dog. A harness that is too big is easy for a wriggly puppy to back out of.
- Replace a harness that has been chewed or has stretched straps.
If you are also choosing a crate, our dog crate size chart explains how to size one for a growing puppy with a divider panel.
How should a harness fit?
Once the harness is on, do a quick check:
- Finger test: you should be able to slide two fingers under the straps, but not much more. The AKC’s wording is that you should have to squeeze two fingers underneath without the harness feeling tight. Its harness-versus-collar guide suggests about one finger for small dogs and two for large breeds.
- Free shoulders: VCA says a well-fitted harness doesn’t limit front-leg movement or rub behind the elbow. It also warns that some front-clip designs sit across the shoulder joints and restrict movement.
- Escape test: if the harness slides over your dog’s head when they back up, it is too loose.
- Skin check: look for rubbed fur or red skin in the armpits and behind the elbows after the first few walks. The AKC lists chafing and restricted movement as signs of a poor fit.
Re-check the fit after grooming, and whenever your dog gains or loses weight, as the AKC advises.
Front clip or back clip?
The AKC describes front-clip harnesses as helpful for dogs that pull, because the leash attaches at the chest and turns the dog toward you. Back-clip harnesses suit dogs that already walk politely on a leash. Dual-clip designs let you start on the front ring and move to the back as your dog improves. The clip doesn’t change your size, but it does change the fit check: make sure a front-clip harness doesn’t sit across your dog’s shoulders.
Harness safety tips
- Take it off when you are not watching: VCA says it is best to remove any harness when your dog isn’t directly supervised, and notes that collars can get caught and twisted in crates and kennels. Tufts University’s vet school likewise says collars and harnesses are fine during play only with close supervision.
- A walking harness isn’t a car restraint: Kurgo’s own page says the Tru-Fit Smart walking harness is not crash tested. In the Center for Pet Safety’s 2013 crash-test study of car harnesses, only one model, the Sleepypod Clickit Utility, earned its top-performer rating. If your dog rides in the car, look for a harness or crate tested for that purpose; our best dog crates for travel guide covers crash-tested options.
- Why a harness at all: Tufts’ vets call a well-fitted harness much preferable to a collar for many dogs, because collar pressure can make breathing harder for flat-faced breeds and aggravate a collapsing trachea in small dogs. Ask your vet what suits your dog.
Frequently asked questions
What size harness does a 50-pound dog need?
It depends on the brand and your dog’s chest. PetSafe’s Easy Walk chart puts 25- to 50-pound dogs in a Medium and 40- to 65-pound dogs in a Medium/Large; Kurgo’s Tru-Fit puts 25 to 50 pounds in a Medium. Measure your dog’s chest girth and check it against the chart for the exact harness.
Should a dog harness be tight or loose?
Snug, not tight. You should be able to fit about two fingers under the straps (about one for very small dogs), and the harness shouldn’t slide over your dog’s head when they back up.
Can I size a harness by weight alone?
Weight gets you close, but every brand we checked says the chest measurement is more accurate. Ruffwear doesn’t list weights at all for the Front Range, only girth.
Are harness sizes the same across brands?
No. Size names and girth ranges differ between makers, and even their advice for dogs between sizes differs. Always use the chart for the specific harness.
How often should I re-measure my dog?
Every few weeks for a growing puppy, and whenever an adult dog gains or loses weight or has a big haircut.
How we chose
This is a research-based guide; we didn’t measure dogs or harnesses ourselves. We compared the AKC’s measuring and fit advice with VCA and Tufts guidance on fit and safety, and with the official size charts PetSafe, Ruffwear, Kurgo and 2 Hounds Design publish for their own harnesses. Where brands disagree, as they do on sizing up or down, we say so. Read our full editorial policy.
Sources and further reading
- Choosing the Right Harness for Your Dog (American Kennel Club): Where to measure the neck and chest for a harness, the two-finger fit check, front-clip versus back-clip designs, and adjusting a puppy’s harness as it grows.
- How to Measure Your Dog for Clothes and Gear (American Kennel Club): Step-by-step measuring guide for chest and neck girth, with the dog standing and two fingers of slack.
- Collar and Harness Options for Dogs (VCA Animal Hospitals): Explains how a well-fitted harness should sit, why some front-clip designs can restrict the shoulders, and why to remove a harness when a dog is unsupervised.
- Dog Collars and Harnesses (Cummings School of Veterinary Medicine at Tufts University): Veterinarians’ view on harnesses versus collars, including risks of neck pressure for flat-faced and small dogs.
- Easy Walk Harness (PetSafe): Manufacturer size chart with chest girth, chest width and approximate weight for each size, plus advice to size up between sizes.
- Front Range Harness (Ruffwear): Manufacturer girth-only size chart and advice to choose the larger size between sizes.
