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An Improved Technique for Determining Bra Size with Applicability to Breast Surgery

Pechter, Edward A. M.D.

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Plastic and Reconstructive Surgery: May 2008 - Volume 121 - Issue 5 - p 348e-350e
doi: 10.1097/PRS.0b013e31816b1286
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Many women express their goals for breast surgery in terms of bra size, yet the traditional method of bra sizing is confusing and inaccurate, with up to 80 percent of women said to be wearing the wrong size bra. In response to this problem, a new system of bra measurement was developed. It is a modified version of a previously reported method of bra sizing that determines cup size by direct breast measurement1 while now allowing for the fact that cup size varies with band size (e.g., the C cup of a size 36 bra is larger than the C cup of a size 34 bra).

With this system, brassiere band size is still determined by the industry standard of “underbust chest circumference plus 5,”2–4 but cup size is determined by the relationship of breast width to underbust circumference. Breast width is measured with a tape from the breast mound’s origin on the lateral chest wall to its termination in the parasternal area. Small or firm breasts can be measured with a woman upright or supine, and large or ptotic breasts are measured with the subject supine.

Breast width and chest wall measurements were studied in relationship to bra fit in more than 1000 women undergoing breast surgery over a period of 5 years, until a consistent relationship between the two was established. The correlation of breast width and underbust circumference to bra size is shown in Table 1. The relationships are most easily understood by examining the “prime” sizes (asterisks in Table 1). For any given underbust circumference, every 1 inch increase or decrease in breast width changes the cup by one size. For example, a woman with a 33-inch underbust and a breast width of 8.5 inches would fit a 38B bra, but if her breast width were 9.5 inches, she would fit a 38C bra.

Table 1:
Bra Size as Determined by Relationship of Breast Width to Underbust Circumference

Conversely, for any given breast width, the cup goes up or down by one size with every alternate step in band size. For example, a woman with a 9-inch breast width and a 31-inch underbust circumference would wear a 36C bra, but if her underbust circumference were 35 inches, she would wear a 40B bra.

The information inTable 1 was used clinically to help meet patients’ breast surgery goals. For example, if a woman with an underbust circumference of 29 inches (34 band size) wished to be a C cup after augmentation or reduction, an attempt was made to enlarge or reduce her breasts to a width of 8.5 inches. Figure 1 demonstrates the difference between the traditional and new methods of bra measurement in a representative patient.

Fig. 1.:
Woman with 500-cc silicone implants. Bust circumference is 36 inches, underbust circumference is 29 inches, breast width is 9.5 inches, bra size by traditional measuring system is 34B, and bra size by new measuring system is 34D. (Above) A 34B bra is too small, gapping across the lower sternum and providing inadequate breast coverage. (Below) A 34D bra fits well.

Breast measurements are helpful in breast augmentation and reduction and in quantifying the difference in size in women with asymmetrical breasts, with each 1-inch increment corresponding to a cup size. Experience has shown that almost every woman will fit the size bra determined to be right for her by this new system, even if she chooses to wear a bra of a different size for personal reasons.

Edward A. Pechter, M.D.

Department of Plastic Surgery

University of California, Los Angeles

Los Angeles, Calif.


1. Pechter, E. A new method for determining bra size and predicting postaugmentation breast size. Plast. Reconstr. Surg. 102: 1259, 1998.
2. The Lingerie Store USA. Bra Fitting. Available at Accessed May 14, 2006.
3. Just My Size. Sizing for Bras and All-in-Ones. Available at Accessed May 14, 2006.
4. Big Girls’ Bras. Fitting Bras. Available at Accessed May 14, 2006.

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