Using a soft tape, measure around the rib cage directly under the bust. The tape should be held tight, edge to edge with no space between it and your body. If you are sagging be sure to support / lift your breasts and have someone help you measure your under bust.
Measure completely around the bust at the fullest point. Hold the tape tight against the back but not too tight in the front.If you are sagging be sure to support / lift your breasts and have someone help you measure your over bust.
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