I purchased this shirt in a form fitted medium. For reference I am 5'4 and weigh 125lbs. I normally wear a small but I've read on other reviews to size up. The medium fit me perfectly and is very form fitted, which is the style that I like. One word of warning, the shirt did shrink in the wash. I think the sleeves are the portion that shrank the most. Not to the point where you can't wear it, but I did notice it when I put it on next. Definitely size up if you're getting the form fitted shirt! It's really comfortable and soft and I love the colors!