Its not especially loose fitting. I wear a medium and I just now tried it on with just a short sleeve T shirt. It fit fine and looked fine. There was some extra room, but not a lot. I'd say you could wear something a little heavier than a T shirt under it, but I wouldn't think you could wear anything too bulky under it. All depends on what you plan to wear under it and if you size up, presumably the sleeves and length will still be right for you. Hope this answered your question. This jacket is a nice shell, average roominess, but especially roomy though.
Answered on 11/22/2014 10:02:50 PM by Larry L from Baltimore, MD
Not a snug fit. I would buy your regular size.
Answered on 11/22/2014 11:20:17 PM by GuitarMan from new england
Yes. Buy up one size. The arms are generous but it is slim waist. I got a Medium and the waist is most likely 32-33" at the bottom. Great jacket, though. It breathes well, packs up small and has some style to it.
Answered on 11/23/2014 12:28:24 AM by Pacific Rider from NA California
Yes, I would suggest going with the larger size.
Answered on 11/23/2014 8:51:43 AM by TBCaddyshack from Connecticut
I would buy a size up to wear over a fleece
Answered on 11/23/2014 3:12:49 PM by WGSDO from Ohio