Length - base of neck (in front of the withers) to tail base
Girth - largest chest circumference behind front legs
Most dogs in the Toy, Miniature, Italian Greyhound, and Whippet sizing have chest that are 2-2.5 inches longer than their length. Greyhound chests can be 3-4 inches longer, and Dachshunds chest can be 3-4 inches longer than their lengths.
If your dog is in between sizes, or very large or small chested, please write the chest size in the comments section of your order, and we will help you figure out the right size for your dog.