Measure under your arms, around the fullest part of your bust
with only the bra on that you intend to wear with your dress.
(Note: Your bra size is not the same as your bust
Measure around your natural waistline. Bend to the side to find the natural crease of your waist. measure at this point. (Approximately 2" above your belly button.)
Measure around the fullest part of your hips and rear. ( Approximately 9" down from your waist measurement.)