Dog harness size calculator
Enter your dog's chest girth, and its neck if you have it. You get the most likely harness size and the matching size on three popular brands' charts, with the reasoning.
Tim de JongWidest part of the rib cage
Optional, helps with overlapping sizes
Optional cross-check
Optional, fills in a typical weight
Most likely size
M
The brands disagree for a 26 in chest, and M is the middle answer. Use the chart of the harness you buy.
The same dog, three brands, sometimes three different letters.
Brand by brand
- Ruffwear Front Range harness: S (22–27 in).
- PetSafe Easy Walk harness: Medium (22–32 in) over Small/Medium or Medium/Large: the chest sits nearer the middle of its range.
- Kurgo Tru-Fit Smart harness: Large (24–34 in) over Medium: it is a tie, so we size up.
Compared with each maker's published chest-girth chart, checked October 2026. Where two sizes overlap, PetSafe says to size up; for the others we pick the size your dog sits nearest the middle of (and the neck fits, if you gave it).
Brand charts were checked on each maker's website in October 2026. Makers change their charts, so confirm with the chart of the harness you buy.
How do you measure a dog for a harness?
Use a soft tailor's tape, or a piece of string you then hold against a ruler. Have your dog stand square on all four feet: the AKC points out that a standing dog has its spine aligned and its weight evenly spread, which gives a truer number than a sitting one.
- Chest girth (B): wrap the tape around the largest part of the rib cage, usually just behind the front legs. This is the measurement every harness chart uses.
- Neck girth (A): wrap the tape around the base of the neck, where a collar sits, starting at the ridge between the shoulder blades and coming round the front of the chest.
- Two fingers under the tape: the AKC's two-finger rule for circumferences. It builds in the room your dog needs to breathe and move.
Measure twice. If you get two different numbers, use the larger one. Growing puppies change size every few weeks, so measure again before each new harness.
Dog harness size chart
There is no industry standard for harness sizes. This table puts the chest-girth ranges from three makers' charts side by side, with the span each letter covers across all three. PetSafe also sells in-between sizes (Petite/Small, Small/Medium, Medium/Large), which the calculator includes.
| Size | Ruffwear Front Range | PetSafe Easy Walk | Kurgo Tru-Fit | Typical span |
|---|---|---|---|---|
| XS | 17–22 in | 12–17 in | 12–18 in | 12–22 in |
| S | 22–27 in | 15–21 in | 16–22 in | 15–27 in |
| M | 27–32 in | 22–32 in | 18–28 in | 18–32 in |
| L | 32–36 in | 27–40 in | 24–34 in | 24–40 in |
| XL | 36–42 in | 32–49 in | 28–44 in | 28–49 in |
Look at how wide the spans are: a "Medium" harness can be made for a chest anywhere from 18 to 32 inches depending on the brand. A letter on its own tells you very little.
Why harness sizes differ between brands
Each maker draws its own size lines, and adjustable straps let one size cover a wide range, so the ranges overlap. Take a dog with a 26-inch chest:
- Ruffwear Front Range harness: S
- PetSafe Easy Walk harness: Medium (fits Small/Medium, Medium, Medium/Large)
- Kurgo Tru-Fit Smart harness: Large (fits Medium, Large)
Where sizes overlap, the calculator picks the one your dog sits nearest the middle of, so there is adjustment left both ways, and breaks a tie by sizing up. PetSafe gives that advice for dogs between two sizes, and Ruffwear says to choose the larger size for a growing puppy. Also check whether a product is sized by your dog's measurements or by the harness's own dimensions: the AKC notes that brands do both.
Can you choose a harness size by weight?
Only as a rough guide. PetSafe and Kurgo print weight ranges next to their sizes, and PetSafe says plainly that they are approximate. Two dogs of the same weight can have very different chests: compare a deep-chested sighthound with a stocky bulldog. Use weight to sanity-check the girth, not to replace it.
| Brand and size | Chest girth | Approx. weight |
|---|---|---|
| PetSafe Petite | 12–17 in | under 10 lb |
| PetSafe Petite/Small | 13–18 in | 10–15 lb |
| PetSafe Small | 15–21 in | 15–25 lb |
| PetSafe Small/Medium | 19–26 in | 20–30 lb |
| PetSafe Medium | 22–32 in | 25–50 lb |
| PetSafe Medium/Large | 24–34 in | 40–65 lb |
| PetSafe Large | 27–40 in | 65–95 lb |
| PetSafe Extra Large | 32–49 in | 90+ lb |
| Kurgo X-Small | 12–18 in | 5–10 lb |
| Kurgo Small | 16–22 in | 10–25 lb |
| Kurgo Medium | 18–28 in | 25–50 lb |
| Kurgo Large | 24–34 in | 50–80 lb |
| Kurgo X-Large | 28–44 in | 80–110 lb |
If you don't know your dog's weight, pick its breed in the calculator to fill in a typical one, or look up the breed in our dog weight chart.
How should a dog harness fit?
Once it is on, you should be able to slide two fingers flat under every strap. The AKC adds that a harness needs enough room that it won't become too tight when your dog pulls. Then check the fit in motion:
- The straps shouldn't sit in your dog's armpits or rub behind the front legs after a long walk.
- Your dog shouldn't be able to back out of it when it stops and pulls backwards.
- Buckles and the leash ring shouldn't press on the throat.
For a collar to go with it, the collar size calculator uses the same neck measurement, and the sweater and coat size calculator uses the chest girth you just took.
Frequently asked questions
What size harness does a 50 lb dog need?
By weight alone, a 50 lb dog falls in Medium or Medium/Large on PetSafe's Easy Walk chart and Medium or Large on Kurgo's Tru-Fit chart. Weight is only a rough guide, though: a deep-chested 50 lb dog and a slim one can need different sizes, so measure the chest.
Should I size up or down for a dog harness?
PetSafe tells owners to choose the larger size when a dog falls between two sizes, and Ruffwear says the same for growing puppies. A harness that is slightly big can be tightened; one that is too small can't be let out.
How tight should a dog harness be?
Snug, with room to slide two fingers flat between any strap and your dog. Check again after a walk, because straps loosen, and leave enough room that the harness doesn't dig in when your dog pulls.
Is chest girth the same as chest width?
No. Girth is the distance all the way around the rib cage. PetSafe's chart also lists a chest width, which is a different measurement. All three charts in this calculator use girth, so that is the number to take.
Do I need my dog's neck size for a harness?
For many harnesses, yes. Kurgo's chart lists neck and chest for each size, and a harness with a strap around the neck has to fit both. Ruffwear's Front Range is sized on chest girth alone. If you only take one measurement, take the chest.
Sources
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