In English, the term Kalimantan refers to the Indonesian portion of the island of Borneo, while in Indonesian, the term "Kalimantan" refers to the whole island of Borneo.

The Indonesian territory makes up 73% of the island by area, and 69.5% (13,772,543 at the 2010 Census of Indonesia) by population. The non-Indonesian parts of Borneo are of Brunei (400,000) and East Malaysia (5,625,000), the latter comprising the states of Sabah and Sarawak. The region within Indonesia is also known as Indonesian Borneo.

Kalimantan's total area is 544,150 square kilometres (210,097 sq mi).

Kalimantan is divided into four provinces:

Provinces in Kalimantan
Province Area (km2) Total population (2000 census) Total population (2005 estimate) Total population (2010 census) Provincial capital
West Kalimantan
(Kalimantan Barat)
147,307.00 4,016,353 4,042,817 4,393,239 Pontianak
Central Kalimantan
(Kalimantan Tengah)
153,564.50 1,801,965 1,913,026 2,202,599 Palangkaraya
South Kalimantan
(Kalimantan Selatan)
38,744.23 2,984,026 3,271,413 3,626,119 Banjarmasin
East Kalimantan
(Kalimantan Timur)
204,534.34 2,451,895 2,840,874 3,550,586 Samarinda