Dog Size Guide – How to Measure for Harnesses, Collars & Apparel

Sizing by breed alone is how you end up with a harness that slips or a collar that chokes. Take three quick measurements with a soft tape measure (or a string you then hold against a ruler) and you'll get it right the first time.

The three measurements

1. Neck

Measure around the neck where the collar naturally sits — lower than the ears, above the shoulders. Add two fingers' width of room. Used for: collars, bandanas.

2. Chest girth

Measure around the widest part of the rib cage, just behind the front legs. This is the most important measurement for harnesses. Used for: harnesses, vests, hoodies, costumes.

3. Back length

Measure from the base of the neck (where the collar sits) to the base of the tail. Used for: hoodies, shirts, costumes, anxiety vests.

General size chart

Sizes vary slightly by product — always check the chart on the product page when one is shown. This is a general guide:

Size	Neck	Chest girth	Back length	Typical weight
XS	8–11 in	12–15 in	8–10 in	3–7 lb
S	10–14 in	15–19 in	10–12 in	7–15 lb
M	13–17 in	19–24 in	12–15 in	15–30 lb
L	16–21 in	24–30 in	15–19 in	30–55 lb
XL	20–25 in	30–36 in	19–23 in	55–85 lb

Between sizes?

• Harnesses and collars: size up. Both are adjustable and a slightly larger one can be tightened; a too-small one can't be fixed.
• Apparel and costumes: go by chest girth first, then back length. If chest says M and length says L, choose L for deep-chested breeds and M for slim breeds.
• Anxiety vests: should be snug, not loose — if between sizes, size down.

Fit check after it arrives

• Collar: two fingers slide under it comfortably; it can't slip over the head.
• Harness: no rubbing behind the front legs; two fingers fit under every strap; it doesn't twist when your dog pulls.
• Apparel: full range of motion in the front legs; nothing pulling at the armpits.

Wrong size? Unused items with tags can be returned within 14 days — see our FAQ.