How US Bra Sizing Works

The United States bra sizing system uses inches for band measurements. Band sizes typically range from 28 to 48, measured around the ribcage directly under the bust. To determine your band size, measure snugly around your ribcage and round to the nearest even number. If you measure 31 inches, your US band size is 32.

US cup sizing follows a letter progression: A (1-inch difference between bust and underbust), B (2-inch), C (3-inch), D (4-inch), DD/E (5-inch), DDD/F (6-inch), G (7-inch), H (8-inch), and so on. Note that after DD, US sizing becomes inconsistent between brands — some use DDD, others use F, some skip to G. This is why knowing your measurements in inches is more reliable than memorizing your cup letter.

For example, a 34C in US sizing means a 34-inch band with a 3-inch difference between bust and underbust, giving a full bust measurement of approximately 37 inches. US sizing is used not only in the United States but also in Canada, Mexico, Brazil, and several Asian markets including Singapore, Philippines, and India.

Compared to UK sizing, US sizing differs primarily at cup sizes above D. A US DDD (or F) is equivalent to a UK E, and a US G is equivalent to a UK F. This means if you wear a US 36G, your UK size would be 36F. When shopping international brands, always check whether the brand uses US or UK sizing — the difference can be 1-2 cup sizes.