I wear a medium in most shirts but I took the recommendation of other reviewers and ordered a large in Fossil color.  I accidentally ordered two.  The order arrived quickly and one of the shirts had a small stain in one spot and small snag in another spot.  I returned the bad shirt and had no issues with the return process through Amazon.  The other shirt is very comfortable, fits great, and looks nice with shorts or jeans.  It doesn't require ironing and feels cool and lightweight even on the hottest days.