- 1). Put on your most comfortable non-padded bra. Take a deep breath and exhale. With the measuring tape parallel to the ground, measure around the bra directly under the bust. This determines your frame size. Round any fractions to the nearest whole number. If the measurement is even, add 4 inches. If it's odd, add 5 inches.
- 2). Stand up and put your arms at your side. Get someone else to wrap the measuring tape around the center of the bra. Round any fractions to the nearest whole number.
- 3). Subtract the breast size in step 2 from the figure in step 1. The resulting number determines your cup size. If the difference is ½ inch or less, the cup size is AA. If the difference is ½ to 1 inch, the cup size is A. The other cups and sizes are B (1 to 2 ½ inches), C (2 ½ to 3 ½ inches), D (4 inches), DD or E (5 inches), DDD or F (6 inches) and G (7 inches).
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