The Ubangi River (/(j)uːˈbæŋɡi/; Swahili: Mto Ubangi; French: Fleuve Oubangui; Dutch: Mubangi Stroom), also spelled Oubangui, is a river in Central Africa, and the largest right-bank tributary of the Congo River. It begins at the confluence of the Mbomou (mean annual discharge 1,350 m/s) and Uele Rivers (mean annual discharge 1,550 m/s) and flows west, forming the border between Central African Republic (CAR) and the Democratic Republic of the Congo (DRC). Subsequently, the Ubangi bends to the southwest and passes through Bangui, the capital of the CAR, after which it flows south – forming the border between the DRC and the Republic of the Congo. The Ubangi finally joins the Congo River at Liranga.
The Ubangi's length is about 1,060 km (660 mi). Its total length with the Uele, its longest tributary, is 2,270 km (1,410 mi). The Ubangi's drainage basin is about 651,915 km (251,706 sq mi). Mean annual discharge at mouth 5,936 m/s. Its discharge at Bangui ranges from about 800 m/s (28,000 cu ft/s) to 11,000 m/s (390,000 cu ft/s), with an average flow of about ~4,000 m/s (140,000 cu ft/s). It is believed that the Ubangi's upper reaches originally flowed into the Chari River and Lake Chad before being captured by the Congo in the early Pleistocene.