Best dog harness: there isn't one, but there is a best size

There is no single best dog harness, because the thing that most decides whether a harness works — whether it fits — depends on your dog's chest, and every brand sizes differently. A harness labelled Medium fits a 38–56cm chest at Puppia and a 69–81cm chest at Ruffwear; ranges that do not even touch. So the useful question is: which harness, in which size, puts your dog in the middle of a range, with the lead clipped where you need it? This guide answers that in four steps, then points to the right guide for your dog.

How this guide was made: we have not tested harnesses on dogs. The figures come from the makers' own size charts — twelve harnesses from eleven brands, each with its source and the date it was read — and the advice from how harnesses work mechanically. How the charts are kept.

Step 1: measure the chest

Round the deepest part of the ribcage, just behind the front legs, with the dog standing and the tape snug against the coat. That one number is what every harness here is sized by. Weight is printed on half the charts, but where weight and chest disagree, the chest wins. How to measure, and what to do when the dog will not stand still.

Step 2: decide where the lead clips

• The dog pulls hard: a front clip on the chest, which turns the dog back towards you when it surges. The no-pull guide compares the six no-pull harnesses on our charts.
• The dog walks reasonably: a back clip is simpler, never tangles round the legs, and takes the load off the neck. Harness or collar? explains why a back clip alone does nothing about pulling.
• Both, depending on the walk: a harness with a ring at the front and the back. Check the listing — clip positions are on the product page, not the size chart.

Step 3: choose the size that puts your dog in the middle

Every size is a range — the span the straps can let out and take in. A dog in the middle of a size has adjustment both ways: room for a winter coat, a few kilos, a puppy's growth. A dog at either end has none, and a dog at the loose end has the slack it needs to back out. So the best size is the one where your dog sits centrally, and the best brand is often the one whose steps happen to fall around your dog's number.

A 68cm chest shows why. At Ruffwear that dog is an S at 92% of its range — nearly let out to the limit. At Julius-K9 it is a 0 at 56%, and at PetSafe an Easy Walk Medium at 48%. Same dog, same tape; very different fits. The size finder takes one measurement and shows this for all twelve charts at once. Between two sizes?

Step 4: fit it when it arrives

Two fingers laid flat under every strap, with the dog standing. Then slide the girth strap forwards: it should stop against the elbows, not climb the ribs. Then pull gently backwards on the harness — the dog should move with it. How tight a harness should be covers each strap.

The right guide for your dog

• A toy breed, or under 35cm of chest: few harnesses go that small, and below 29cm only one does. Best harness for small dogs.
• A giant breed, or over 100cm: most harnesses stop between 96 and 112cm, and past 124.5cm only one is made. Best harness for large dogs.
• A deep-chested build — Greyhound, Whippet, Doberman, Dachshund: weight points to a size that is too small. Sizing a deep-chested dog.
• A dog that escapes: almost always a fit failure, not a clever dog. Why dogs back out of harnesses.
• A growing puppy: buy the size that puts today's chest near the bottom of its range, and re-measure every two to three weeks. Saving your dog's size keeps the record and estimates when the size runs out.

The twelve harnesses at a glance

What each maker's chart covers, so you can see who even makes a size for your dog:

Harness	Chest covered	Sizes	Weight printed
Julius-K9 IDC Powerharness	29–138cm	9	Yes
PetSafe Easy Walk	30.5–124.5cm	8	Yes
Wonder Walker No-Pull	34.3–121.9cm	6	Yes
Kurgo Tru-Fit Smart	30–112cm	5	Yes
PawSafe Steady+Style	45.7–111.8cm	5	Yes
Blue-9 Balance	34–110.5cm	5	No
PetSafe Easy Walk 3 in 1	33–108cm	4	Yes
Ruffwear (one chart for its harnesses)	23–107cm	7	No
Dog Friendly Co No-Pull	39–103cm	6	No
Top Paw Mesh Comfort	33–99.1cm	6	No
Rabbitgoo ControlPro No-Pull	29.5–96.5cm	5	No
Puppia RiteFit	33–80cm	4	No

Each brand page has the full chart, its source and the date it was read. For how far apart the charts really are, see how much harness size charts disagree.