I never mentioned size in the review below. I purchased XXL Shirt Jacket

The only thing better than the material used to manufacture these clothes is the exceptional craftsmanship shown putting the pieces together. I’m 5’9”on a good day and 250lbs before breakfast. Other than the sleeves being a little long the fit is comfortable and leaves just enough room for a light vest. The pockets are the right size and placed perfectly. The jacket seems to clean itself. The dirt stays on the surface then falls of. I am a fan of shirt jackets and 1620 has made by far the best shirt jacket I have worn. And last but not least exceptional customer service and more than fair policies round it all out. *****

I am medium and it fit perfectly. Mind you, it’s slim fit.

I'm 6'2" and ~190 pounds.
I got one in large. It fit but was a bit short and tight for my taste. Went up two sizes to XXL, much better.

I'm 6'2" and ~190 pounds. I got the large. It fits fine, but if I could do it over again I'd probably size up (I prefer looser fit, and a little more length).
It's thicker than other work shirts I've worn.
I don't know if it was intentional, but on the inside there's two large side pockets. You could fit most books inside one of them.