My Stats: My weight in the summer runs 160 and around 170 in winter. I'm about 165 now.. I'm 5' 9" 3/4 (?) I'm medium to small frame. I don't have a large stomach. I'm pretty much a true Medium fit. This Jacket is a Medium. It fits perfect. "It cannot be any smaller or larger." Zipped up it is snug, but fits good and movable. For those they may be interested in purchasing, they customize.