Usually buying clothes online is a hassle as it can be annoying not being able to verify fitment and returns. First, clothing must be sold in US size. I have the XXL and it fits like a large, they should be snug on the chest and arms, flow in the middle and be a bit longer than regular t-shirts.
Gildan Performance Men's π Clothing and Shirts with Moisture-Wicking Polyester
44 Review
Men'S Regular Fit Short-Sleeve Dress Shirts By Allsense - Look Stylish And Professional!
41 Review
Calvin Klein π Herringbone Sleeve Men's Dress Clothing
50 Review
H2H Mens Casual Slim Fit Short Sleeve T-Shirts Cotton Blended Soft Lightweight V-Neck/Crew-Neck
46 Review