Breasts typically stop growing in the late teens to early twenties. Most commonly, breast growth concludes around age 18 to 19, usually about two years after the first menstrual period. However, the exact age varies among individuals due to genetics, hormones, nutrition, and overall health. Some may experience breast development continuing into their early twenties. After this natural growth phase, breasts might still change in size and shape over a lifetime due to factors like weight fluctuations, pregnancy, breastfeeding, and aging, but the main growth period usually ends by the early twenties.