Measure your dog's neck with a fabric measuring tape (or a piece of string and a ruler). You should allow enough space for two fingers to be placed easily between the dog's neck and the measuring tape. This measurement is your guide in choosing the correct collar from the size ranges below. There are a couple of sizes that overlap to give you more options. For example, the XS toy and XS regular are the same length and differ only in width. This allows you to choose smaller or larger hardware so that you get the perfect fit for your dog!