Purnia, city, northeastern Bihar state, northeastern India. It lies east of the Saura River, a tributary of the Ganges (Ganga) River.
Purnia is a major rail and road junction and is heavily engaged in agricultural trade. The region is one of the major jute-producing areas of India, and such crops as grains, tobacco, and oilseeds are also important. In the city of Purnia, rice milling and jute milling are the major industries. Purnia was constituted a municipality in 1864 and has a state hospital. Pop. (2001) 171,687; (2011) 282,248.