Collar size and fit for my dog
Updated 15 October 2026
In short: measure the neck with a soft tape, halfway down, where the collar will sit, without pulling tight. Choose the size whose adjustment range includes that measurement, ideally near the middle. Once the collar is on, two flat fingers should fit underneath, and it shouldn't slip over the ears. Check every week for a puppy, every month for an adult.
Why size matters so much
It restricts and irritates
- Coughing, trouble swallowing or breathing
- Broken hair, redness, sores
- The dog scratches and resists wearing it
It slides and lets the dog escape
- The dog backs out of it
- A paw or jaw can get caught in it
- The tag gets lost with the collar
Measuring your dog's neck
- Use a soft tape measureOr a piece of string that you then measure flat against a ruler.
- Place it halfway down the neckWhere the collar will rest, not against the head and not at the base of the shoulders (that's where a harness goes).
- Measure without pulling tightThe tape touches the neck without pressing in. On a long-haired dog, flatten the coat.
- Choose the sizePick the size whose range includes the measurement. If you're on the border between two sizes, take the one where it falls nearer the middle; for a puppy, keep room to grow.
Not sure about your measurement? Our size calculator gives you the collar, harness and lead size in seconds.
Our collar sizes
| Size | Polyester collar | Waterproof collar | Example breeds |
|---|---|---|---|
| S | 28–43 cm · 1.5 cm wide | 27–36 cm · 1.6 cm wide | Poodle, Pinscher, Spitz, Pekingese, Cavalier King Charles, Papillon |
| M | 33–51 cm · 2 cm wide | 32–47 cm · 2 cm wide | French Bulldog, Staffy, Setter, Pointer, Beagle, Shiba, Pug, Border Collie |
| L | 41–66 cm · 2.5 cm wide | 42–63 cm · 2.5 cm wide | Golden Retriever, Australian Shepherd, Husky, Akita, Labrador, Beauceron, Malinois, German Shepherd, Boxer |
See our patterned collars and waterproof collars.
The two-finger rule
With the collar fastened, slide two flat fingers between the collar and the neck. They should fit without forcing, with no room for a third. Then do the ear test: pulling the collar gently forwards, it shouldn't slip over the head.
Too tight. Loosen it a notch or a few centimetres and test again. If it's already at its longest, go up a size.
Perfect. Check it doesn't slip over the ears, then repeat the check regularly.
Too loose. Tighten it. If it's already at its shortest, go down a size: a collar that's too big will end up slipping off.
Checklist: does the collar fit well?
With the collar on:
When to recheck the fit
- Before the first walkAlways check a new collar, even if it's the right size.
- PuppyEvery week: it can change size within weeks.
- AdultEvery month, and after any weight gain or loss.
- After grooming or moultingA shorter or thicker coat changes the fit.
A dog that pulls? Even perfectly fitted, a collar passes the pull to the throat. For the lead, choose a Confort Y harness and keep the collar for the tag.
Frequently asked questions
How do I measure my dog's neck for a collar?
With a soft tape, halfway down the neck where the collar sits, without pulling tight. Choose the size whose range includes that measurement.
Should I add centimetres to the measurement?
With an adjustable collar, no: choose the size whose range includes the measurement, then adjust to keep two fingers of room.
My dog is between two sizes: which one?
The one where the measurement falls nearer the middle of the range. For a puppy, the one that leaves more room to grow.
How do I know if the collar is too tight?
If two fingers don't fit, or if it coughs, scratches or has broken hair underneath. Loosen it and test again.
How often should I check a puppy's collar?
Every week, because it grows fast.