The Vils arises from the confluence of the Großer and Kleiner Vils. The two source rivers arise in Upper Bavaria in the district of Erding and unite 700 meters south of Gerzen, in the area of the municipality of Schalkham, near the district of Wörthmühle, where the last mill of the same name is located on the Große Vils.
The Vils is 68.62 km long. The valley of the Vils is dominated by agriculture and there are several hydroelectric power stations on the river. At Frontenhausen it flows in a nature reserve through the Vilstalsee, which is also used for local recreation. A few kilometers later it divides into the new Vilskanal and the Altvils, which reunite and divide several times in the further course. Its largest tributary is the Kollbach, which flows out at Kröhstorf. At Vilshofen the river finally flows into the Danube at river kilometer 2248.7.