The river Amper south of Fürstenfeldbruck
|Main source||Northern Limestone Alps|
48°30′1″N 11°57′24″E / 48.50028°N 11.95667°ECoordinates: 48°30′1″N 11°57′24″E / 48.50028°N 11.95667°E
|Basin size||3,100 km2 (1,200 sq mi)|
|Length||185 km (115 mi)|
The Amper (known in its upper reaches as the Ammer) is a river in southern Bavaria, Germany – the largest tributary of the Isar river. The Amper flows in a generally north-eastwards direction, reaching the Isar in Moosburg, 185 kilometres (115 mi) from its source in the Ammergau Alps, with a flow of 45 m³/s. It runs through the Ammersee; upstream of the Ammersee it is known as the Ammer. Its major tributaries are the Glonn (located near Augsburg), the Würm (the outflow of Lake Starnberg), and the Maisach.