Don't really know how to answer your question, but I purchased the XL. I'm 6'6" at 220lbs and this does me well. I can easily fit it over my hunting layers if it's cold.
Good Luck,
Craig
__________________
Being in my treestand puts me 15 feet closer to God
I just got mine in a medium. I'm 5'10" 170 lbs. The medium Mfits about right for me, but I'm not sure how much I could wear under it. I tried a large L before that, but had to send it back as it was much too baggy, and much too long for me.
I'm worried more about the length. I'm 6'4, and i think i have long legs. All the hunting pants i have ever boughten are not long enough. Thats the main concern. Does this suit have belt loops?
These things have extra-long legs...at least in my opinion. I had to pull my pants all the way up to my chest, just so I wasn't tripping over the legs. The pants have an elastic all the way around that fit snug wherever you pull them to.