I got a size M, and the fitting was perfect. I personally like to wear my T-shirts a little loose, so I don't think you'll need to go a size up unless you're wanting an oversized T-shirt. The quality is much softer even though the product is 100% cotton. (i think). My shirt came in so quick as wlell!
Rated 5 out of 5
Rated 1 on a scale of minus 2 to 2, where minus 2 is Runs Small, 0 is True to Size and 2 is Runs Large