For fitting reference: Model is 6'2" 185 lbs wearing a brand new unwashed size Medium in all photos, for a fitted look (with only a t-shirt underneath).
Model also comfortably wore a size Large (for a standard fit after washing and drying).
Our tips: Order your usual size for a standard fit. Size down for a fitted athletic look. Size up for a roomy fit or layering with undershirt and long-sleeve tees etc.