The Leiblach is a 34-kilometre-long (21 mi) tributary of Lake Constance (Obersee) and the Rhine, respectively. It forms the Austria–Germany border near the lake.

The Leiblach source is near the German municipality of Heimenkirch, flowing to the southwest. Near the Austrian town of Hohenweiler, the river joins a small tributary, the Rickenbach [ceb; sv]. This tributary forms a part of the Austrian-German border, and below the confluence the border continues to follow the Leiblach until it eventually empties into Lake Constance between the German town of Lindau and the Austrian village of Lochau.