Do you wanna know how long are basketball quarters? Then the simple answer is, each quarter typically lasts 12 minutes in professional leagues. But, in some leagues or levels of play, the duration of quarters may vary. For example - in international basketball competitions, quarters might be 10 minutes long. Also, there are college basketball games where quarters are 20 minutes. Some stoppages like -  timeouts, and potential overtime periods, can make the actual duration longer.