How to Measure Your Dog for a Coat or Jacket (Sizing Guide)

Most owners measure back length first, ring up the brand size that matches, and end up with a coat that twists, slides or chokes the dog around the shoulders. Back length tells the brand where to cut the fabric. Chest girth is the measurement that decides whether the coat actually fits. Get that one right and the rest of the sizing chart sorts itself out.

You need three measurements: back length (collar to base of tail), chest girth (widest point behind the front legs), and neck (where the collar sits). Use a soft tape, leave two fingers’ space between tape and body, and size up if you fall between sizes. Chest girth is the most important – if a coat fits the chest, the rest is fixable.

A badly sized coat doesn’t just look off. A coat that’s too tight chafes under the front legs and limits stride; a coat that’s too loose twists sideways, exposes the belly to wind, and stops the dog squatting to toilet. Once that happens most dogs refuse to wear it again, so the second coat purchase costs you the first one too. We’ve seen this play out across every body shape – from the long-back dachshund to the deep-chested staffy – and the fix is always the same five minutes with a tape measure before you click buy.

The three measurements every brand asks for

Every reputable brand sizing chart – Petstock’s chart guide is a clean AU example – uses the same three numbers. Take them once, write them on your phone, and you can shop any brand confidently.

• Back length. Base of the collar (between the shoulder blades) to the base of the tail. This sets the coat’s coverage – too short leaves the rump exposed; too long blocks the dog from squatting.
• Chest girth. The widest point of the rib cage, just behind the front legs. This is the make-or-break measurement. If the chest fits, the coat sits stable across the back; if it doesn’t, nothing fixes the fit.
• Neck. Where a normal collar sits – the base of the neck, not the top. This sizes the neck opening so the coat doesn’t ride back or rub the trachea.

Each one runs by the two-finger rule. After the tape is settled, you should be able to slide two fingers (flat, side by side) between the tape and the dog without forcing them in. Less than that and the coat will chafe. More than that and it’ll drift.

How to take each measurement

Use a soft tape measure. No tape? A length of string or shoelace works – mark the spot with a finger or a pen, then measure it against a ruler afterwards. Stand the dog square on all fours, head up but relaxed. A second person to feed treats helps.

1. Back length first. Hold the zero end at the base of the collar – the natural dip between the shoulder blades. Run the tape flat along the spine to the base of the tail (where the tail joins the body, not the tip). Record in centimetres.
2. Chest girth second. Pass the tape under the dog just behind the front legs, around the widest part of the rib cage, and back to where you started. It’s easy to slip the tape too far back into the belly – feel for the bony rib cage and stay there. Two fingers gap, then record.
3. Neck last. Sit the tape where the everyday collar sits – at the base of the neck, just above the shoulders. Don’t measure the top of the neck behind the ears; that’s where the head is widest, and you’ll oversize the coat. Two fingers gap, record.

For a long-coated breed – a cavoodle fresh out of a groom looks 4cm slimmer than the same dog two months in – press the tape lightly through the coat so you measure the body, not the fluff. For a small dog, kneel on the floor to keep the tape flat; standing over them tilts the tape and inflates the chest reading.

What to do if your dog won’t stand still

Most puppies and a fair number of adults can’t hold a stand for sixty seconds. Try this order: tire them out first with a short walk, measure on a non-slip surface (rug, towel on hard floor), and feed a slow treat by hand at head height while a second person takes the tape around. A treat lure pulls the neck and spine into the right shape for measuring.

If you’re solo, measure the dog asleep – curl the tape around the chest while they’re on their side, then double-check the neck and back length when they get up to investigate. Imperfect numbers from an awake dog beat perfect numbers from one being wrestled.

Reading a sizing chart (and what to do between sizes)

Every brand presents the chart slightly differently. Some lead with weight, some with back length, some with chest. Ignore the weight column – it’s the least reliable indicator across breeds. Match chest girth first, then check the back length column matches your number within 2cm either side. If those two line up, the size is usually right.

Between sizes? Size up. A coat one notch too big rides slightly long but the chest sits clean – a coat one notch too small pulls under the armpits within an hour. Brand sizing also drifts: a ‘medium’ in one brand is often a ‘small’ in another, so don’t assume your last coat’s size carries across.

For short-coated breeds with long bodies (dachshund, basset, corgi-cross) check whether the brand makes a long-bodied cut. Pet Circle and Petstock both stock ranges designed for sighthound and dachshund proportions, and the standard chart simply won’t fit those dogs.

Which AU dogs actually need a coat

Not every dog needs one. AU vets generally point to dogs that benefit most when overnight temperatures drop below 14°C or so, which covers most winter mornings and evenings south of Brisbane.

• Cold-sensitive small breeds: Italian greyhound, whippet, miniature pinscher, chihuahua, dachshund, toy poodle.
• Senior or arthritic dogs of any size – joint stiffness in the cold is real.
• Short-coated medium and large breeds: greyhound, boxer, staffy, vizsla.
• Recently clipped or post-surgery dogs through the first cold spell after their procedure.

Dogs that almost never need one in AU conditions: heavy double-coats like the husky, samoyed, malamute, German Shepherd, golden retriever, and the working Australian breeds (kelpie, ACD). Their coat is doing the job a jacket would do, and an extra layer over a double coat traps moisture against the skin. The exception is a brief, light rain shell on a winter walk – not a heavy insulated jacket.

If you’re unsure, follow the AU vet rule of thumb – if your dog shivers, tucks the tail and refuses to settle outside, they’d benefit from a coat. If they trot around happily at 8°C, they don’t need one.

Fit problems and what they tell you

• The coat twists sideways after five minutes. Chest girth is too loose. The coat needs to grip the rib cage to stay aligned.
• The dog freezes or hunches when you put it on. Usually a too-tight neck or armpit cut. Take the coat off and check both with the two-finger rule.
• The rump is exposed even when sitting square. Back length is short. This is the easiest sizing mistake to make on a long-bodied dog.
• Chafing or thinning hair under the front legs. The leg openings are too tight, the chest is too small, or the cut isn’t shaped for your dog’s build – common when short-coated breeds wear a generic ‘medium’ cut.
• The coat slides back off the shoulders. Neck opening is too loose. The chest fastening is doing all the work and the front of the coat collapses backwards.
• The dog can’t squat properly. Either the coat is too long, or it sits too low on the belly. Most male coats are cut shorter on the underside – check before you buy if your dog is desexed female and the brand only lists ‘unisex’.

FAQ

Save your dog’s three measurements in the notes app on your phone, with the date. Then you can shop any brand, in any season, without re-measuring – and you’ll spot the day they grow out of a size before the next coat arrives in the wrong fit.