30DD

30DD is a bra size used in many North American sizing systems. It combines a band size of 30 inches with a cup size described as DD (double D). The DD designation indicates a larger cup relative to the band than a D cup, reflecting greater bust volume for the same band measurement. Sizing systems and cup lettering can vary by brand, region, and style.

Measuring for a 30DD typically involves two measurements. The underbust measurement around the ribcage determines the band size, while the overbust measurement at the fullest part of the bust helps estimate cup volume. In practice, many retailers advise trying on multiple sizes and styles, because a 30DD can fit differently across brands and bra cuts. Cup volume is influenced by cup shape, padding, and the construction of the bra, not just the label.

Regional and brand variations mean the exact equivalent of 30DD can differ. Some brands may translate DD into a different letter or combine it with a slightly different band size in other markets. Because fit can vary widely, customers are encouraged to consult brand-specific size charts and to try a range of styles, including full-coverage and demi-cup designs. Proper fit is indicated by centered breasts, a smooth breast shape without spillage or gaps, and comfortable band support without riding up the back.