Sizing and Fit: How to Measure Your Dog or Cat
Most returns in this category are a fit problem wearing a product problem's coat. Five minutes with a tape measure prevents nearly all of them. Here is the short version, with links to the detailed guide for whatever you are actually buying.
Measuring for a collar
Wrap a soft tape around the middle of your dog's neck. Not down at the base near the shoulders, not up behind the ears. That middle point is where a collar settles of its own accord.
Pull it firm enough to compress the coat, then add two fingers' width. On a long-haired or double-coated dog this matters more than anything else on this page, because coat can easily be hiding three or four centimetres of pure air.
No tape measure in the house? A strip of paper or a shoelace, marked with your thumbnail and laid flat against a ruler, works perfectly.
The full method, with a breed chart and what to do about sighthounds, is in our dog collar size guide.
Measuring for a harness
Two numbers. Girth is the widest part of the chest, just behind the front legs, and it is the one that picks the size. Neck is the base of the neck, where a collar sits.
If the two point at different sizes, take the larger and adjust inwards. Taking up slack is easy. Adding length has never once worked.
Chest shape also decides which style fits at all, and the breed-by-breed version lives in our harness fit guide.
Measuring a cat
Neck at the midpoint, and girth behind the front legs if you are buying a harness. Fit a cat collar looser than a dog collar, two to three fingers underneath, and never walk a cat on a collar.
The safety detail, including an honest note on which of our collars are and are not breakaway, is in the cat guide.
The two-finger rule, properly explained
Everybody repeats it and almost nobody says how. Lay two fingers flat, side by side, between the collar and the neck, parallel to the collar rather than poked underneath at an angle.
Flat is the whole trick. Two fingers wedged in vertically is a much bigger gap than two fingers laid flat, and that difference is roughly the difference between a collar that stays on and a collar that goes over the ears in a car park.
When your dog lands between two sizes
Collars: take the smaller size if your measurement sits in the lower half of its range. Collars adjust down better than up, and a collar living on its last hole has nowhere left to go.
Harnesses: take the larger and adjust in.
Puppies: buy for now. A collar bought to grow into is unsafe for every month before it fits, and puppies outgrow things faster than the collar wears out.
How often to check again
Weekly for a puppy. Monthly for an adult. After any seasonal moult for a double-coated breed. And after any real weight change, which includes the winter most dogs quietly have.
Common questions
Should I measure the neck or just use my dog's weight? Measure. Weight charts are a rough proxy and they are wrong often enough to matter, especially for stocky small breeds and lean big ones.
What if my dog will not stand still? Measure while they are eating, or get a shoelace round in one pass and mark it with a thumbnail instead of trying to read a number off a moving target.
Do Pawd sizes run large or small? They run to the number on the chart. Every size on this site is stated as a neck or girth range in centimetres rather than a letter on its own, so you can check your measurement against it directly.
The collar fits but it spins around. Is that normal? A little rotation is completely normal. If the buckle ends up underneath within a minute of every walk, it is one hole too loose.
