I ordered the size XS for my dog (14lbs, 15" girth) and while the fit was great (not too tight, not too loose), it was way too long for him. I contacted Ruffwear and they said the XXS may be better since it's 3" shorter. The exchange process was very fast and easy. Unfortunately, while the XXS was the perfect length, it was way too tight on my dog and I could tell he was uncomfortable. He has a unique body type and I have been having a hard time finding him a warm jacket. This is a great coat and Ruffwear's customer service is beyond great, it just didn't work out for us.