The town is located in the Tennengau region south of the City of Salzburg, stretching along the Salzach river in the shadow of the Untersberg massif, close to the border with Germany in the west. With a population of about 20,300, Hallein is the second largest town of the Salzburg state. The municipal area comprises the cadastral communities of Adnet II, Au, Burgfried, Dürrnberg, Gamp, Gries, Hallein proper, Oberalm II, and Taxach.