Bust measurement is taken around the apex or fullest part of the bust
Waist measurement is taken at the natural waist, the smallest part of your abdomen; above your belly button and below your ribs. If you bend from side to side, you bend at your natural waist.
Abdomen measurement is taken at the top of your hip bone, around your belly button level.
Hip measurement is taken at the fullest part of your bottom. If you’re an average height, about 9 inches below your waist.