How to Measure Your Dog for the Perfect Collar Fit
A collar that's even a centimetre out can mean months of a dog escaping, rubbing, or point-blank refusing to wear it. We see the emails: "it fit in the box, why doesn't it fit now?" Almost every time, it comes down to how the neck was measured in the first place, not the collar itself.
We make every collar to measure here in Yorkshire, which means we talk our customers through sizing more than most shops ever have to. This guide is everything we'd tell you if you called us up and asked, "right, how do I actually do this properly?"
Where Should a Dog Collar Actually Sit?
Before you measure anything, it helps to know where a collar is meant to sit, because this trips more people up than you'd think.
A standard everyday collar, buckle or clasp, sits at the mid-neck. Roughly halfway between the base of the skull and the top of the shoulders. Not jammed up under the chin, not sitting loose down near the shoulders.
Martingale collars are the exception. They're designed to sit slightly higher, closer behind the ears, because their whole job is different, more on that below.
What You'll Need
- A soft fabric tape measure. The kind you'd find in a sewing kit.
- No tape measure? A piece of string or an old shoelace works. Wrap it round, mark where it meets, then lay it flat against a ruler.
- A calm dog. Standing, not sitting or lying down.
That last point matters more than people expect. A dog sitting or lying down curls their neck and shoulders in a way that throws the measurement off by a surprising amount. Get them standing, treat in hand if needed.
How to Measure Your Dog's Neck, Step by Step
Step 1: Stand your dog naturally
Weight evenly on all four feet, not leaning into you, not twisted round to see what you're doing. A helper holding treats at nose height works wonders here.
Step 2: Wrap the tape at the mid-neck
Bring the tape around at the point where the collar will actually sit. Snug, not tight. Once it's wrapped, slide two flat fingers underneath, side by side. If they fit comfortably without a fight, you've got the right tension. This is the two-finger rule, and it's the single most useful check in this whole guide.
Step 3: Record the measurement in centimetres
Note the number down straight away. Dogs get bored fast, and "I'll remember it" rarely survives the walk back from the utility room.
Common Measuring Mistakes
A handful of things account for nearly every wrong-size order we see:
- Measuring while the dog is fidgeting. A wriggling dog gives you a different number every time. Take two or three measurements and go with the most consistent one.
- Measuring over thick fur instead of against the skin. For double-coated breeds especially (Huskies, Golden Retrievers, Samoyeds), fur can add a surprising amount of bulk to the tape measurement. Smooth it down first so you're measuring the neck itself, not the coat sitting on top of it.
- Not accounting for a seasonal coat blow. This one catches people out every spring. A collar fitted snugly against a full winter coat can end up loose once that coat sheds out. If your dog's had a big seasonal blow-out, it's worth rechecking the fit rather than assuming last year's size still holds.
- Confusing a collar's flat, laid-out length with how it actually fits once buckled. If you've ever laid a collar flat on the table and measured it end to end, that number is not the same as the neck size it fits once it's wrapped round and fastened. This trips up more people than anything else on this list, always measure your dog, not the collar.
- Not accounting for a growing puppy. More on this below.
Why Narrow-Necked Breeds Need Extra Care
Some breeds, particularly sighthounds like Whippets, Greyhounds, and Lurchers, have necks that are close in circumference to their heads. That difference matters more than you'd think, because it means a standard flat collar, correctly sized, can still slip backward and off over the head the moment the dog pulls back or startles.
This isn't a training issue or a fitting mistake. It's simply the shape of the breed. It's exactly the problem Martingale collars were designed to solve, the collar tightens slightly under tension, enough to stop it sliding over the head, without ever choking. If you've got a sighthound, or any dog with a head not much wider than their neck, we'd genuinely steer you toward a Martingale collar rather than a standard fitting, regardless of how well you measure.
Why Collar Width Matters as Much as Length
Getting the neck measurement right is half the job. The other half, and something almost nobody talks about, is width.
Our range runs from a slim 15mm up to a substantial 38mm, and the right width isn't just about looks:
| Breite | Best suited to |
|---|---|
| 15mm | Toy and small breeds, puppies |
| 20mm | Small to medium breeds |
| 25mm | Medium to large breeds |
| 38mm | Large and giant breeds |
A correctly sized but too-narrow collar on a big, strong dog concentrates pressure into a thin band, which is far less comfortable under any real pulling force than a wider collar spreading that same load across more surface area. If you've got a Labrador or a Newfoundland, don't just chase the right neck measurement, look at our Extra Wide Tweed range built specifically for bigger dogs.
Does Collar Material Affect Fit?
Yes, and it's another thing most sizing guides skip entirely.
- Biothane doesn't stretch at all. What you measure is what you get, permanently. Get this one right, since there's no forgiveness built into the material.
- Harris Tweed softens very slightly with wear, the way a good pair of boots breaks in. Not enough to change which size you order, but enough that a collar can feel that touch more comfortable after a few weeks of use.
- Rope collars are made to your exact measurement, so they're the most forgiving option if your dog sits right on the edge between two standard sizes.
Browse Biothane, Harris Tweed, or Rope collars to see the full range in each material.
Dog Collar Size Chart by Breed
A useful starting point, though every dog is different, always trust your own tape measure over a chart.
| Breed examples | Typical neck size | Suggested width |
|---|---|---|
| Chihuahua, Miniature Dachshund | 18cm – 28cm | 15mm |
| French Bulldog, Cockapoo | 23cm – 36cm | 20mm |
| Cocker Spaniel, Border Collie | 28cm – 43cm | 20-25mm |
| Labrador, Golden Retriever | 36cm – 51cm | 25mm |
| Staffordshire Bull Terrier, German Shepherd | 46cm – 66cm | 25-38mm |
| Newfoundland, Great Dane | 46cm – 76cm | 38mm |
Sizing for a Growing Puppy
Puppies don't grow at a steady rate, so a size that fits today might not fit in a month, especially for large and giant breeds who pack on growth fastest early on. As a general rule, check the fit more often while your puppy is young, roughly every few weeks, and more frequently still for a fast-growing large breed.
It's tempting to size up "so they've got room to grow," but a collar that's genuinely too loose brings its own risks, slipping off, catching on things, or simply not doing its job if your puppy escapes. Better to size correctly for now and re-measure as they grow. Our Small Breed Biothane Collars are a gentle, lightweight starting point for most puppies.
What If My Dog Is Between Sizes?
Size up rather than down, and pop a note in at checkout letting us know your exact measurement. If you're still not sure, just get in touch before you order, we'd always rather help you get it right the first time than sort out an exchange after.
Häufig gestellte Fragen
What size collar does my dog need?
Measure around the mid-neck with a soft tape measure, snug enough that two fingers slide underneath comfortably. Match that measurement against our size chart, and choose a width suited to your dog's size and strength.
How do I know if a collar is too tight or too loose?
Too tight: you can't comfortably fit two fingers underneath, or you see rubbing or hair loss where it sits. Too loose: it slides around the neck, or your dog can work a paw or their head through it.
Why does my dog keep slipping out of their collar?
Usually either the collar is fitted too loose, or your dog has a narrow head-to-neck ratio (common in sighthounds), in which case a Martingale collar is the safer, purpose-built solution rather than tightening a standard collar further.
Can a Biothane collar be adjusted if I measure wrong?
Biothane doesn't stretch or give, so if the size is wrong, it stays wrong. If you're between sizes or unsure, get in touch before ordering, or consider a Rope collar instead, which is made to your exact measurement.
Getting the measurement right takes two minutes and saves weeks of a collar that rubs, slips, or just isn't quite comfortable. Once you've got your number, browse our full range of dog collars and find the right fit, material, and width for your dog. And if you're ever unsure, drop us a message, we measure collars for a living, we're happy to help you get yours spot on.
