After many purchases and returns from Ruffwear and others, we finally found the perfect coat for our Supermutt. He is long and lean. About 60 lbs., 29" chest, 27" long. We had originally ordered a Med. (we followed the sizing chart) but it didn't go down the entire length of his back which is what we wanted. Ruffwear made the exchange so easy! We got the large and since we are able to shorten the sides that goes around his chest, it is perfect. LOVE that you can tuck the ends of the straps inside and never have to fuss with them once it fits. We have never put a coat on our dog but since it has been below zero for weeks here in Northern New England we decided he needed one. It is so easy to get on and off and since he is not used to wearing a coat, that is an extra bonus. Would highly recommend this coat!!