You've probably done it — bought a collar based on your dog's breed, or copied the size off an old one that's gone stiff and worn, only to find it's either loose enough to slip over their head at the park or tight enough to leave a mark by the end of the walk. Sizing a dog collar isn't complicated, but it's easy to get slightly wrong, and with leather especially, slightly wrong doesn't fix itself the way a stretchy fabric collar might.
Get the measurement right once and you won't think about it again. Here's exactly how to do it, along with a full size chart and the extra things worth knowing if you're choosing a leather collar rather than a synthetic one.
Table of Contents
- Why Getting Dog Collar Sizing Right Matters
- How to Measure Your Dog's Neck for a Collar
- Dog Collar Size Chart by Breed
- Collar Width — Why It Matters as Much as Length
- How to Tell If a Collar Is the Wrong Size
- Sizing a Leather Collar
- Caring for a Leather Collar So the Fit Lasts
- Frequently Asked Questions
- Final Thoughts
Why Getting Dog Collar Sizing Right Matters
A collar has one job: stay on securely without being uncomfortable. That balance is harder to hit than it sounds, and it matters more with some materials than others. A stretchy fabric or elasticated collar has a bit of built-in forgiveness — it'll flex a little if you're out by a centimetre. A leather collar won't. It holds its shape from day one, which is exactly why the leather softens and moulds to your dog over time rather than stretching out of shape, but it also means the size you buy is the size you're committing to.
Undersized, and you risk rubbing, chafing, or pressure on the trachea, especially on dogs that pull. Oversized, and the collar can spin around the neck, ride up towards the ears, or — worst case — slip off entirely if your dog backs away from something. Neither is a small issue. A correctly sized collar should feel snug enough that it can't come off over the head, loose enough that it doesn't restrict breathing or movement.
How to Measure Your Dog's Neck for a Collar
You don't need anything specialist for this — a soft tape measure works best, but a piece of string and a ruler does the job just as well.
Step by Step
- Measure at the base of the neck, where the collar will actually sit day to day — not further up near the ears, where the neck is usually narrower.
- Wrap the tape snugly, not tightly. You want it to sit the way a fastened collar would, not pulled taut.
- Apply the two-finger rule. Slide two fingers flat underneath the tape. If they fit comfortably but you can't easily get a third finger in, that's your number.
- Round up, not down, if your measurement falls between two sizes. A collar that's a fraction loose is a quick buckle adjustment; a collar that's a fraction tight is a return.
If your dog is still growing, take this measurement every few weeks rather than assuming last month's size still holds, and lean towards an adjustable style until growth has levelled off.
Dog Collar Size Chart by Breed
Breed is a useful starting point for narrowing down a size, but it's exactly that — a starting point. Individual dogs vary a lot even within the same breed, so treat this as a guide to check your own measurement against, not a substitute for taking it.
| Size | Length | Width | Typical Breeds |
|---|---|---|---|
| XXS | 35cm | 1.5cm | Chihuahua |
| XS | 40cm | 1.5cm | Jack Russell |
| S | 45cm | 1.5cm | Beagle |
| M | 50cm | 2.5cm | Border Collie |
| L | 55cm | 2.5cm | Labrador |
| XL | 60cm | 2.5cm | German Shepherd |
If your dog's neck measurement sits between two rows, go with the larger of the two and rely on the buckle to fine-tune the fit.
Collar Width — Why It Matters as Much as Length
Length gets most of the attention, but width changes how a collar actually feels and performs day to day.
A narrower width (around 1.5cm) suits smaller, lighter-boned dogs — it sits comfortably without looking oversized or feeling heavy against a slighter neck. A wider width (around 2.5cm) is built for dogs with more strength behind them: it spreads pressure across more surface area, which makes a real difference on a dog that leans into the lead or pulls on walks.
If you're buying a collar and lead as a set, it's worth matching the widths so the pull feels consistent and the pieces look intentional together, rather than mismatched.
How to Tell If a Collar Is the Wrong Size
Even with careful measuring, it's worth knowing the warning signs either way.
Signs a Collar Is Too Tight
- You can't comfortably fit two fingers underneath it
- Fur is rubbing away or the skin looks irritated where the collar sits
- Your dog coughs, gags, or seems reluctant when the lead is clipped on
Signs a Collar Is Too Loose
- It rotates freely around the neck rather than sitting in one place
- It can be worked up towards the ears with gentle pressure
- Tags or hardware hang noticeably low or swing when your dog moves
If you're seeing any of the tight-collar signs, size up immediately — don't wait it out hoping the leather will loosen with wear.
Sizing a Leather Collar
Everything above holds true regardless of material, but a genuine leather collar is worth a specific mention, because it behaves differently from fabric or synthetic webbing over time.
Full grain leather doesn't stretch to compensate for a slightly loose fit the way elasticated materials do — instead, it softens and develops character with use while holding its original dimensions. That's part of what makes it last, but it also means accuracy at the point of buying matters more than it would with a stretch collar. Measure carefully, round up rather than down, and the fit you buy is the fit you'll have for years rather than months.
If you're drawn to a hand-embroidered style rather than a plain strap, the pattern itself has a genuinely interesting backstory worth a read once you've got sizing sorted.
Caring for a Leather Collar So the Fit Lasts
Correct sizing only holds up if the leather is looked after. Wipe the collar clean with a damp cloth after muddy walks and let it air dry naturally, away from direct heat, which can cause leather to dry out and stiffen unevenly. An occasional application of a leather-safe balm keeps the hide supple and helps prevent cracking at the fold points — particularly around the buckle, where the leather flexes most.
Frequently Asked Questions
How do I measure my dog's neck for a collar?
Wrap a soft tape measure around the base of the neck, snug but not tight, then check you can fit two fingers comfortably underneath. Round up to the nearest size if you're between two measurements.
What size collar does my dog need based on breed?
Small breeds like Chihuahuas typically need an XXS (35cm), while larger breeds like German Shepherds usually need an XL (60cm), with sizes in between for breeds like Beagles, Border Collies, and Labradors. Always confirm against your dog's actual neck measurement rather than breed alone.
How do I know if a collar is too tight or too loose?
Too tight shows up as rubbing, coughing, or difficulty fitting two fingers underneath. Too loose shows up as the collar spinning freely or working its way towards the ears.
Should I size up for a growing puppy?
Re-measure every few weeks during growth and choose an adjustable collar where possible, rather than assuming one size will last through the whole growing period.
Do leather collars stretch over time?
Not in the way fabric or elasticated collars do. Leather softens and develops a patina with use, but it holds its original size — which is why getting the measurement right at the point of buying matters more with leather than with stretch materials.
What's the difference between narrow and wide collar widths?
Narrower widths suit smaller, lighter dogs, while wider widths distribute pressure better for larger dogs or stronger pullers.
Final Thoughts
Sizing a dog collar properly takes a couple of minutes and saves you from buying twice. Measure at the base of the neck, apply the two-finger rule, and use breed as a rough guide rather than the final word. If you're after a collar built to hold that fit for years rather than months, browse our full range of leather dog collars, leads, and matching sets, handmade from full grain leather in six sizes.