When no size chart is involved and the description says both "men's" and "unisex", you can find yourself a little confused as to which size you need.  I was hoping other reviews would give me a clue, but I didn't find any by people with my dimensions.  I am a 5'10", 145 lb female... usually wear a medium or large depending on the store.  Decided to go with a small and it fit perfectly.  The length of the sleeves and coat itself was great, and it was close-fitting, but not tight, which is important when you're working around open flames.  For the price, the quality is good.  Overall, a solid purchase for a college microbiology lab course!