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Written and reviewed by the Choco & Friends team in Auckland, New Zealand ยท Last updated 8 October 2026
The short answer: harness size comes down to one number, your dog's chest girth in centimetres. Measure around the widest part of the ribcage, just behind the front legs, then match it to the chart below. Breed is a good starting guess, but two dogs of the same breed can be two sizes apart, so always measure.
Choco here. I've worn more harnesses than I can count, and the ones that rubbed, slipped or let me back out all had one thing in common: someone guessed the size. Here's how to get it right the first time, with sizes for New Zealand's most popular breeds.
Step 1: Measure your dog (2 minutes)
You need a soft tape measure (a phone charger cable and a ruler work too) and a treat.
- Chest girth (the one that matters most). Wrap the tape around the widest part of the ribcage, about two fingers behind the front legs. Keep it snug, not tight.
- Neck. Measure where a collar sits, around the base of the neck.
- Weight (optional). Handy as a cross-check, but never choose a harness on weight alone. A 9 kg Frenchie and a 9 kg Beagle need different sizes.
Want the full walkthrough with pictures? Read our How to Measure Your Dog guide.
Step 2: Match the chest to our harness size chart
This is the size chart for the Wagster Harness. Every Wagster harness is adjustable at the neck and chest, so each size covers a range.
| Size | Chest girth (cm) | Neck (cm) | Typical dogs |
|---|---|---|---|
| XS | 36โ48 | 29โ36 | Chihuahua, Maltese, Toy Poodle, puppies |
| S | 41โ54 | 35โ44 | Shih Tzu, Jack Russell, Cavalier, Mini Schnauzer |
| M | 46โ61 | 39โ51 | French Bulldog, Spoodle, Cavoodle, Beagle |
| L | 57โ83 | 42โ56 | Border Collie, Staffy, Boxer (smaller) |
Between two sizes? Size up, then use the adjusters to get a snug fit. The only exception: if your dog is fully grown and their neck clearly fits the smaller size, the smaller one gives a more escape-proof fit.
Step 3: Dog harness size by breed (NZ & AU favourites)
These are typical adult chest girths for New Zealand and Australia's most popular breeds. Use them to sense-check your measurement, not to replace it. Crosses like Spoodles and Cavoodles vary the most, because they depend on the poodle parent.
| Breed | Typical chest girth (cm) | Wagster size to start with |
|---|---|---|
| Chihuahua | 30โ40 | XS (under 36 cm: check the fit closely) |
| Maltese and Maltese cross | 33โ43 | XS |
| Toy Poodle | 36โ46 | XS |
| Shih Tzu | 40โ50 | XS or S |
| Jack Russell Terrier | 40โ50 | XS or S |
| Cavalier King Charles Spaniel | 45โ55 | S |
| Miniature Schnauzer | 45โ55 | S |
| Cavoodle | 45โ60 | S or M |
| French Bulldog | 50โ65 | M (L if over 61 cm) |
| Spoodle and Cocker Spaniel | 50โ65 | M |
| Beagle | 55โ65 | M or L |
| Border Collie | 65โ80 | L |
| Staffordshire Bull Terrier | 65โ80 | L |
| Boxer | 75โ90 | L up to 83 cm |
| Labrador and Golden Retriever | 80โ95 | L only if 83 cm or less |
| German Shepherd | 85โ100 | Larger than our range |
An honest note from Choco: our harnesses are made for small and medium dogs, and the L tops out at 83 cm. If your Lab or Shepherd measures bigger than that, please don't squeeze them in. Choose a brand that makes a true XL.
Step 4: Check the fit at home
Put the harness on, adjust it, then run these four checks before your first walk:
- Two-finger rule. You should slide two flat fingers under every strap, no more.
- No rubbing. The straps sit clear of the armpits and don't press on the throat.
- No backing out. Gently pull the lead forward. The harness shouldn't slide over the head.
- Free shoulders. Your dog can walk, sit and trot without the straps twisting.
Red flags: redness or hair loss under the straps means too tight or rubbing; the harness spinning sideways means too loose.
Sizing a puppy
Puppies can change size in weeks. Measure every two to three weeks, buy for the dog in front of you (not the one you expect), and leave room on the adjusters to let it out as they grow. Most small breeds reach close to adult chest size by about 9 to 12 months, and larger breeds keep filling out after that.
Quick answers
What size harness does a French Bulldog need?
Most adult Frenchies measure 50โ65 cm around the chest, which is a Wagster M. Frenchies are deep-chested, so if yours measures over 61 cm, go L.
What size harness does a Cavoodle need?
Usually S or M. Cavoodles range from about 45 to 60 cm, so measure first.
What size harness for a Spoodle?
Most adult Spoodles are a Wagster M (50โ65 cm chest).
Should I choose a harness by weight or by measurements?
By measurements. Chest girth is what decides the fit; weight is only a rough cross-check.
Where do I measure my dog's chest for a harness?
Around the widest part of the ribcage, just behind the front legs.
My dog is between sizes. Which one?
Size up and use the adjusters to get a snug fit. Only go smaller if your dog is fully grown and their neck clearly fits the smaller size.
How tight should a dog harness be?
Snug enough that two flat fingers fit under each strap, and loose enough that it never rubs.
Ready to choose?
Got your number? Find your size in the Wagster Harness, or grab the whole set (harness, leash, bandana and doo-doo holder) in the Wagster Style Pack. We ship from Auckland, with free shipping over $89 across New Zealand and Australia. More of Choco's everyday advice is on our Choco's Tips page.
Breed figures are typical adult ranges compiled from published manufacturer size guides. Individual dogs vary, so measure yours before you buy.
