Originally Posted by J. Cogburn
You could just go and try one on. No other way to know for sure.
If there's no store near you, just order the small and return it for a medium if it doesn't fit.
My experience - which is limited - is that J. Crew stuff is sized just a bit on the trim side, but not excessively so.
I can't - I live in England and as far as I'm aware they don't have any shops here?? Otherwise I definitely would go and...