Average Breast Size in the U.S.: Cup Size, Volume, and Natural Variation

Reported Average

According to the American Society of Plastic Surgeons and lingerie industry data, the average U.S. bra size is 34DD (often reported as C/D cup depending on methodology).

Volume Equivalents

Cup volume varies by band size (sister sizes):

• 34C ≈ 32D ≈ 36B ≈ 125–175 mL per breast
• 34DD ≈ 32DDD ≈ 36D ≈ 250–350 mL per breast

Note: Bra sizing is inconsistent across brands; "average" is a rough estimate.

Sources of Variation

• Genetics (major)
• BMI / weight changes
• Hormonal status (cycle, pregnancy, lactation, menopause, OCPs)
• Age (development → involution)
• Ethnicity (population-level differences)

No "Ideal" Size

Breast size is highly individual. Health, comfort, and personal preference matter more than averages. Surgical planning uses 3D imaging and patient goals, not population norms.