This sweater fits my dog perfectly. I purchased the size exactly for her measurements and it fits great. She is a Chihuahua Dachshund mix, and weighs about 14 pounds. I have found that the snugger her clothing fits, the more relaxed she feels, as she does have a bit of anxiety! This sweater is not too snug nor too loose and does have some stretching room. It's perfect! The quality of the material is very nice and Moopers and I couldn't be happier!!