I'm 5'4\" and weigh 165 lbs so I ordered a size up; they aren't thin and tight in the armpits or elbows. Well made, high quality comfortable material, lightweight but opaque; great price. This is a great top for running in mild weather or wearing under a vest in cooler weather. Wash in cool/cold water, mild liquid detergent and very light fabric softener and tumble dry low. The mail arrived quickly.