Medium fits like 42R, sleeves are slight big and long
"I'm 6' tall, 180 lbs, wear a 42R blazer, and 16 neck 34/35 slim fit dress shirts. The medium fit me well, though the sleeves were slightly bigger in circumference and a tad longer than what i prefer and what i have in my other chore coat (Taylor Stitch Ojai in 42). If your biceps aren't real thick, you may find the sleeves a little on the baggy side. Check out the fit on the models. I partially solved this problem by wetting the sleeves then putting the jacket in the dryer on high heat. I also used the 2nd button on the cuffs to keep the sleeve from going past my wrists. That improved the fit and I think it looks pretty good now."





