How to measure your dog for a collar that actually fits

The most common email we get is about sizing, and almost every one of them starts the same way: he's a Labrador so I ordered a large.

Breed is a bad proxy. We have measured working Labradors at 41cm and show Labradors at 53cm. Two dogs of the same breed, same age, same weight, two different collar sizes. A tape measure removes the argument.

Measuring the neck

Use a soft tailor's tape. If you do not have one, a shoelace and a ruler works — wrap, pinch, lay it flat.

1. Find where the collar actually sits. Not up under the jaw, and not down on the shoulders. It is the base of the neck, roughly where a scarf would sit, about two-thirds of the way down.
2. Wrap the tape flat. Snug against the coat, following the line of the neck rather than cutting across it.
3. Slide two fingers flat underneath. Flat, side by side, not stacked. That is the ease you need — enough that the collar cannot be backed out of, not so much that it rides up over the ears.
4. Read the number where the tape overlaps. That is your neck measurement.

If your dog has a thick winter coat, measure again in spring. A Newfoundland can lose two centimetres of apparent neck when the undercoat goes.

Which size to take

Our collars are quoted as a range, not a single number, because every one has five adjustment holes spaced 2cm apart.

• S — 30 to 36cm. Dachshund, Jack Russell, Cavalier, small terriers.
• M — 36 to 43cm. Border Collie, Whippet, Spaniel, Beagle.
• L — 43 to 52cm. Labrador, Retriever, Boxer, Ridgeback, Shepherd.

If you land between two sizes, take the larger. A collar on its tightest hole still fits. A collar that has run out of holes does not.

Measuring the chest for a harness

Different measurement, different place. Run the tape around the deepest part of the ribcage, immediately behind the front legs, and take it snug. That is the girth number our harnesses are sized on.

• S 40–52cm  ·  M 50–66cm  ·  L 64–82cm  ·  XL 78–98cm

The ranges overlap on purpose. A deep-chested, narrow dog like a Whippet often sits at the top of one range and the bottom of the next — either will fit, and the smaller one will look better.

The two-finger rule, and why it matters

Too loose is more dangerous than too tight. A collar a dog can back out of is the single most common way a dog gets loose near a road, usually at the exact moment something startles them and they pull backwards rather than forwards.

Too tight is uncomfortable and, over months, wears the coat away underneath. Two flat fingers is the line between the two, and it has been the standard in saddlery for a very long time because it works.

Growing puppies

A puppy will outgrow a first collar. That is not a reason to buy something disposable.

Buy for the size they are now, on one of the middle holes, and check the fit every two weeks — a puppy can go up a hole in a fortnight during a growth spurt. When they run out of holes, send it back and we will punch a longer strap or swap the size. We would rather do that than sell you three collars.

Still not sure?

Email the two numbers — neck and chest — and roughly what your dog is like on a lead. We will tell you which size to take, and if a harness would suit you better than a collar we will say so, even though the harness is not always the more expensive one.