I'm 5'5", 130 lbs normally wear a 4-6 in bottoms. I bought the large and it fits perfectly. I like that it covers my butt. I read where other people felt they needed to wear a normal bikini bottom under it, however, they must have thinner bird legs than me because this was not an issue. I was adequately covered. Also, the front goes up high enough to help with my mom belly.