Save Yourself Time and Frustration - Please MEASURE your pet before ordering Each brand of dog collar has their own sizing method. To make sure you are ordering the correct size of this collar, please do not measure your dog's previous collar. We recommend using a cloth measuring tape and measure your dog's neck where the collar would normally sit, not high by their ears or too low where their chest and shoulders meet. The measuring tape should wrap around your dog's neck without slack. You do not need to worry about the 'two finger' rule. If you do not have a cloth tape, use a piece of string, or a shoelace and measure with a ruler after you determine the fit. Extra Large - 22" to 27" for extra large breeds like Saint Bernards, Mastiffs and RottweilersLarge - 17" to 21" for large breeds like Labradors, Pitbulls, Bulldogs, German Shepherds and Retrievers Medium - 13" to 17" for medium breeds like Beagles, Dalmatians, Spaniels and PoodlesSmall - 10" to 12"for small and toy breeds like, and Maltese, Jack Russell Terriers, and DachshundsExtra Small - 9" to 10" for extra small and teacup breeds like Chihuahuas, Yorkies, Pomeranians