Why does one breast seem bigger than the other in my bra?

One breast may seem bigger than the other in your bra due to breast asymmetry.

Breast asymmetry — where one breast differs in size, shape, or position from the other — affects the majority of women and is completely normal and natural. Breasts respond uniquely to hormonal changes during puberty, menstruation, pregnancy, and menopause, which can temporarily or permanently influence their size and shape. Genetics, weight fluctuations, and the natural aging process also contribute to breast differences, with tissue becoming less elastic and more fatty over time.

These variations often become more noticeable in certain bra styles, as each breast fills the cup differently, creating the appearance of one breast being larger than the other.