I took a gamble and purchased the small because it was the only sized they had available at the time of purchase. I love the way the small fits and it's not too tight for me (I usually wear a medium). For reference, I'm 5'1" 175lbs and curvy (34d bra, 31 waist, 41 inches at the butt). I wear a lot of Fashion Nova dresses and post them on my IG @Collins2Collins if someone wants to reference my size. I will be wearing and posting this dress within the next month or two.