Bra sizing can be confusing, especially the DD cup size, which is often misunderstood as representing a universally large breast volume. Understanding a DD cup requires looking beyond this label to its underlying mechanics. Proper bra sizing is important for comfort and support, making it beneficial to clarify its nuances.
Deciphering the DD Cup
The “DD” in bra sizing indicates a specific measurement difference, not a fixed breast volume. A DD cup typically corresponds to a 5-inch difference between the bust measurement (around the fullest part of the chest) and the band measurement (around the ribcage directly under the bust).
A DD cup does not represent a static volume across all band sizes. For instance, a 32DD and a 40DD accommodate vastly different breast volumes, even though both are labeled DD. The cup volume is relative to the band size, meaning a DD on a smaller band holds less breast tissue than a DD on a larger band.
DD in Context: Comparing Cup Sizes
To understand the DD cup, compare it with neighboring sizes and their volume progression. Bra cup sizes generally increase incrementally, with each letter representing an additional inch in the difference between bust and band measurements. A D cup signifies a 4-inch difference, a DD cup indicates a 5-inch difference, and a DDD (or F in some UK/European sizing) cup represents a 6-inch difference.
A DD cup is one size larger than a D cup and one size smaller than a DDD/F cup. For example, a 34DD will have a slightly larger volume than a 34D, and a 34DDD will have an even greater volume. This shows that cup volume consistently increases with each letter as long as the band size remains constant.
Accurate Measurement for DD
Determining an accurate bra size, including a DD cup, involves two key measurements: the band size and the bust size. To measure the band, wrap a soft measuring tape snugly around your ribcage, directly under your breasts, ensuring it is level across your back. For consistency, measure while wearing a lightly lined, non-padded bra. If this measurement is an odd number, rounding up to the nearest even number is often recommended.
Next, measure your bust by wrapping the tape around the fullest part of your breasts, keeping the tape level and not too tight. Once both measurements are obtained, subtract the band measurement from the bust measurement. A 5-inch difference between these two measurements typically corresponds to a DD cup size in many sizing systems. For instance, a 30-inch band measurement combined with a 35-inch bust measurement would result in a 30DD bra size.
Beyond the Label: Finding Your Perfect DD Fit
Even with accurate measurements, finding the perfect DD fit requires attention to how a bra feels and performs on the body. A properly fitting bra will have a band that is snug and level across the back, providing the majority of the support (approximately 80%). The cups should fully contain breast tissue without any spillage over the top or sides, nor should there be gaping or wrinkling in the fabric. The center panel, known as the gore, should lie flat against the sternum without lifting away from the body.
Common fit issues for DD cups and larger sizes include underwires digging into breast tissue, straps slipping or digging into shoulders, and the band riding up the back. If the band rides up, it might be too loose, indicating a need for a smaller band size. Conversely, if cups gape, they may be too large or the wrong shape, while spillage suggests the cups are too small. Adjusting the band size often requires a corresponding change in cup size to maintain the correct volume, a concept known as “sister sizing”.