I normally wear a large or extra large depending on article of clothing and brand. After reading posted reviews of this I chose the larger (extra large) hoping for a bit of wiggle room. This can be zipped but it is tight. I need to loose a few pounds for there to be any wiggle room. I do not look like that model in the picture. My point is even if you go up a size it may not be enough. All that aside, I do like this jacket. I love the color and how it is  put together. It is well made and I am sure will be waterproof.