I got the XL since all the reviews mentioned it falling on the small size.  It was definitely XL, but the shirt is meant to be form fitting, snug.  So, if you're looking to 'hide' mommy bellies, this isn't the shirt for you.  I suggest getting the male t-shirt, which is made more square. Not a quality made shirt, one sleeve is longer than the other, but it'll do for one night while my supergirl and I go trick or treating.