I usually wear either a size XL or XXL. I ordered an XXL just to be safe but when I received the shirt, it actually fits like a LARGE (not even an XL). The shirt looks and feels great, but you'll need to go at least one size up. The label lists this shirt as "Classic Fit" XXL. I returned it.

I really like all of the Penguin wear I've purchased. You have to be careful with some of their shirs as some are "classic" fit and others are a "athletic" fit. This shirt is Classic so I bought an XL and it fits perfect. In the athletic fit, always go a size up.