My Boston Terrier is 16.5lbs, has an 18” chest and 15” long back and the size small fits wonderful! I took off one star only because it doesn’t cover her whole back. However she’s not a huge fan of clothes but seemed to accept this one :)Do not regret buying this product. It's very soft. Only "issue" is it gets very stringy and puffy after a few wears. Over all would reccomend.My maltipoo even would come to me when I pulled it out. Ordered for a grand canyon vacation due to I had to get her hair cut just before we left . Lucky it fit perfectly because it snowed this MarchIt's a really is a pretty sweater!! Super thick and warm for the coldest day. I thought it would be a lot softer but it feels a bit stiff. I ordered a size S. It seemed to fit perfectly!!! But about an hour or so later, it had stretched so much, my fur girl had slipped out of it. I tried to put it back on but same thing- she got out of it. It fit her like a large now. Waste of money. But at least I got nice birthday pics with her wearing it.My miniature poodle stayed warm in this cute, soft sweater.The sweater is adorable and the quality is great. My only issue is that the neck part is so big and bulky. It's like a huge turtle neck. My dog can actually get out of it in a matter of minutes. It's almost like she walks right through it. I may try to cut and hem it to fit a little better. I ordered her an XS (what she always wears) and every other part of the sweater fits fine!☺️☺️☺️☺️☺️????Cute sweater but I wanted an Aran type sweaterIt has sliver threads going through it so it’s a little sparklyThe jumper arrived early which was great. It comes in a really handy plastic wallet with a zip. Doubly great as the delivery people had just thrown it over the fence! The jumper itself is gorgeous. Lovely and soft. Poppy certainly didn't mind wearing it. The jumper even has a gap in it so she can wear it over her harness which is always a plus. Only criticism is I would like it a bit longer in the back