I am 6’2” and 195. Pretty much medium frame. In Sitka (tops) either L or XL. Their stuff is designed to be layered, so that has to be factored in, although sizing is inconsistent. In the Fanatic jacket, I am a L. In the Jetstream and Traverse jackets, an XL. In the heavyweight hoodie, a L. Really in between, varies.
I really like Sitka products, but you should try them on, if able. Sitka is pricey, so I like to try things on at retail stores, then order online. Take advantage of sales promotions, eBay , etc… I doubt the retailers appreciate that practice, however, I always walk out with a shopping bag. They are making money on me for other things.