Measure around the dog’s head at the widest part the collar will need to slip over (1). This is usually under the jaw and over or right in front of the ears. These collars have about 2-3 inches of adjustability, but are not fully adjustable, so accurate measuring is important. Collar should be big enough to slip over the head when fully extended, but smaller than the smallest part of the neck (2) when fully contracted. Examples of breeds for each size are generalized examples. A larger or smaller dog within that breed may require a different size.
XSM - 8”-11” (Papillion, Italian Greyhound, Chin, etc.)
SM - 11”-14” (Whippet, Wire Fox Terrier, Norfolk Terrier, etc.)
MED - 14”-17” (Vizsla, Dalmatian, Afghan, Saluki, Greyhound, etc.)
LG - 16”-20” (Doberman, Boxer, Standard Poodle, German Shepherd, etc.)