Tumkur is an administrative district in the state of Karnataka in India. The district headquarters are located at Tumkur. The district occupies an area of 10,598 km² and had a population of 2,584,711, of which 19.62% were urban as of 2001. It is a one and a half hour drive from Bangalore, the capital of Karnataka.
The area of the district is 4158 m². It consists chiefly of elevated land intersected by river valleys. A range of hills rising to nearly 4,000 feet (1,200 m) crosses it from north to south, forming the watershed between the systems of the Krishna and the Kaveri. The principal streams are the Jayamangala and the Shimsha. The mineral wealth of Tumkur is considerable; iron is obtained in large quantities from the hillsides; and excellent building-stone is quarried. The slopes of the Devarayanadurga hills, a tract of 18 m², are clothed with forests, in which large game abounds, including tigers, leopards, bears and wild hog. The annual rainfall averages 39 inches.