The Wang River has its source in the Phi Pan Nam Range in Wiang Pa Pao District, Chiang Rai Province.

From Lampang, the river flows southwards passing by Thoen into Tak Province.

Tributaries of the Wang include the Mo, Tui, Chang, and Soi Rivers The Wang basin is part of the Greater Ping Basin and the Chao Phraya Watershed.

The total land area drained by the Wang River and its tributaries is 10,792 square kilometres (4,167 sq mi).

[1] Kiu Lom Dam (เขื่อนกิ่วลม) is on the Wang River about 38 kilometres (24 mi) from Lampang town.