These delightful little pajamas are lightweight with 4 legged construction that will provide your pet with full coverage. Great for bedtime, after bath time or just lounging around. Helps protect the furniture and car sets from unwanted fur. Available in boy or girl color tones. Sizes are measured from the base of the neck to the base of the tail. You should go by the size your pet is accustomed to, but you may find the following a helpful guide:
Petite: 6-8" (2.5-5 lb) Small: 8-11" (5-8 lb) Med: 10-12" (8-12 lb) Large: 12-16" (13-20 lb) X-Lrg: 16-19" (20-31 lb) 2X-Lrg: 20-23" (32-50 lb)

Tips for accurate measurement: The base of the neck is basically where the collar would go on your pet.
Tip of tail: Go to the beginning of the tail, but not all the way to the end! Chest: Start about an inch behind the front legs and then go around the chest. Use appropriate measuring instruments: A yard stick is an example of a bad one. If you do not have a measuring tape, you could try using string and then put it on a yard stick.