It rises in the hills of Franconian Switzerland, near Haag and flows generally northwest through the towns Creußen, Bayreuth, Heinersreuth and Neudrossenfeld.

The Red Main rises 10 kilometres (6.2 mi) south of Bayreuth near Hörlasreuth (Creußen) in the Lindenhardt Forest at a height of 581 m above sea level (NN).

Beyond Bayreuth the Red Main flows northwest in wide meanders through a broad valley, past the villages of Heinersreuth and Neudrossenfeld.

Information boards on the bridge describe the rest of the river's course, the local walking and cycle routes and the surrounding countryside.

In the vicinity of the Bodenmühle mill east of Bayreuth the Red Main has carved out a bluff (Prallhang) on a bend in the river caused by erosion, the so-called Bodenmühlwand,[2] a steep slope 20 metres (66 ft) in height.

In the latter, geologists found fossils of ostracods (Palaesteria minuta), after which the layers are named (in German), the remains of coelacanth as well as the scales, teeth and fin spines of prehistoric sharks.

Its 60 kilometre long route is as follows: Source of the Red Main-Creußen-Eimersmühle-Schlehenberg-Eremitage-Bayreuth-Martinsreuth-Altenplos-Grüngraben-Jöslein-Langenstadt-Affalterhof Katschenreuth-Steinenhausen Castle near Kulmbach (confluence with the White Main).