A single-breasted garment is a coat, jacket, vest, or similar item having one column of buttons and a narrow overlap of fabric. In contrast, a double-breasted coat has a wider overlap and two parallel rows of buttons. Single-breasted suit jackets and blazers typically have two or three buttons (jackets with one or four buttons are less common), and a notch lapel. However, from the 1930s onwards, peaked lapels on a single button jacket have been variably in fashion. The width of the lapels is one of the most changeable aspects of the jacket, and narrow peak lapels on single-breasted jackets became popular during the 2000s.

Single- and double-breasted jackets
Barack Obama and Recep Erdoğan wearing single-breasted suits.