This oh-so lightweight silk kimono ups your night game, making it impossible for anyone to look elsewhere. To find out what bra cup size you should order, calculate the difference between the bust and underbust cicumferences. Bust: Place the tape under the arms around the fullest part of the bust while wearing a non-padded bra. Waist: Measure around the narrowest part of your waist. Hips: Measure around the fullest part of your bottom at the top of the leg.