Small: Height - 8", Length - 12"
Medium: Height - 12", Length - 14"
Large: Height - 15", Length - 17"
Choose the bag with large enough dimensions (height and length) that your dog can fit into it. Said differently, select the smallest bag that is large enough to accommodate your pup's height *and* length. If your dog is taller or longer than any of the bag's dimensions, you need to size up.
Example 1: if your dog is 11" tall and only 9.5" long, you need the Medium size because your pup is too tall for the Small.
Example 2: if your dog is 11" tall and 16" long, you need the Large size because your pup is too long for the Medium.
If you have measured your dog and need advice, email us at email@example.com and we'll help you find the right bag.