The question of how many cubic centimeters (cc) are in a specific bra cup size is common, but it highlights a significant difference between two measurement methods. Bra cup sizes are a relative system used in retail, while cubic centimeters are a direct and universal measure of physical volume used in medical and surgical contexts. A direct, universal conversion from a cup letter to a fixed volume is impossible because bra sizing is not standardized. Surgeons rely on the fixed unit of cc for planning procedures like breast augmentation.
Understanding Volume and Relative Measurements
Cubic centimeter (cc) is a precise unit of volume measurement, exactly equivalent to a milliliter (ml). This unit is an absolute measure; a volume of 300 cc is the same regardless of the shape or container holding it and is independent of the body’s overall size.
Conversely, the bra cup size system is not based on absolute volume. Cup size (A, B, C, etc.) is determined by the difference between the circumference measured around the fullest part of the bust and the circumference of the under-bust (or band). For example, in many common sizing systems, a one-inch difference corresponds to an A cup, a two-inch difference to a B cup, and a three-inch difference to a C cup. This means the cup letter is a ratio relative to the ribcage, not a fixed volume of breast tissue.
Why Cup Size is Relative to Band Size
The ratio-based nature of bra sizing explains why a single cup letter, such as a C cup, does not represent a consistent physical volume across all wearers. The actual volume of the cup is highly dependent on the band size, which is the number portion of the bra size. For example, a 36C bra contains a significantly larger volume than a 32C bra, even though both are labeled “C” cup. This occurs because the C cup represents a three-inch difference between the bust and under-bust, but the base circumference is much smaller for the 32 band than for the 36 band.
The concept of “sister sizes” further illustrates this relativity. A 34C, a 36B, and a 32D may all contain approximately the same cup volume. This occurs because as the band size decreases by one unit, the cup letter increases by one to maintain the volume, and vice versa. This proportional scaling means the cup letter designates projection relative to the chest wall, not a stand-alone measure of breast volume. Studies measuring breast volume confirm that a range of volumes correspond to the same bra size, and that the volume of any one cup size is not uniform across different band sizes.
Estimating Volume: Bra Size to CC Conversions
Despite the non-standardized nature of bra sizing, plastic surgeons and manufacturers rely on general approximations to translate between the two systems. Industry consensus suggests that each consecutive increase in cup size corresponds to an additional volume of approximately 150 cc to 200 cc. This estimates the volume needed to achieve the next cup letter increase, not the total volume of the breast itself. For instance, if a person is a B cup and desires a C cup, an implant volume in this range is considered a starting point for discussion.
Studies measuring actual breast volume suggest that an average total breast volume for a C cup might be around 500 cc per breast, though this figure varies widely. Research indicates the mean volume increase per cup size is closer to 130 cc to 150 cc. Narrower band sizes require slightly less volume increase than wider band sizes for the same cup jump. These figures are broad averages, and the exact volume of natural breast tissue at any given cup size varies based on anatomy and the specific bra brand’s sizing method.
Surgical Context: Using CC Measurements for Implants
In breast augmentation, cubic centimeters are the definitive unit for measuring implant volume. Implants are measured in cc because this unit is standardized, unlike the inconsistent cup sizes found between different bra brands and countries. Surgeons use the cc measurement to precisely plan the surgical outcome, which is more reliable than relying on an abstract cup letter.
The surgeon selects a specific cc volume for the implant, often ranging from 100 cc to 800 cc, to achieve a desired increase in breast size. A patient may desire to go from a B cup to a D cup, which the surgeon translates into a required cc volume, often 300 cc to 400 cc. To help patients visualize the final result, surgeons use tools like 3D imaging or external implant “sizers.” These are temporary forms placed inside a bra to demonstrate how a particular cc volume will project on the patient’s body. The final cup size achieved after surgery combines the patient’s existing breast volume and the fixed cc volume of the implant.