The river is about 240 kilometres (150 mi) long, and has its source in Gullered, Västergötland, at a height of 332 metres (1,089 ft) above sea level.

The drainage basin covers an area of 3,343 square kilometres (1,291 sq mi), mostly consisting of forest.

The river passes through several minor lakes in Västergötland (Sörsjön, Nolsjö, Vinsarpsjö and Lönnern).

As the tributaries named Lillån join the river, it grows considerably in size.

The drainage basin include the major parts of Falkenberg, Svenljunga, Tranemo and Ulricehamn Municipalities.