city, central Madhya Pradesh state, central India, situated around a lake. Sagar was founded by Udan Singh in 1660 and was constituted a municipality in 1867. A major road and agricultural-trade centre, it has industries such as oil and flour milling, sawmilling, ghee (clarified butter) processing, handloom cotton weaving, bidi (cigarette) manufacture, and railway and engineering works. An old Maratha fort located there (completed in 1780) now houses a police training school. The city also has an industrial school and a school of horsemanship and is the seat of Doctor Hari Singh Gour University (1946) and several affiliated colleges.

Sagar lies in an extensive plain broken by low, forested hills and watered by the Sonar River. Wheat, gram (chickpeas), sorghum, and oilseeds are the chief crops of the region; there is extensive cattle raising. Sandstone, limestone, iron ore, and asbestos deposits are worked. The archaeological site at nearby Eran has revealed several Gupta inscriptions. Pop. (2001) city, 232,133; urban agglom., 308,922.