Arable land availability for agricultural extensification is a determining factor to achieve Indonesia's food self-sufficiency and to become the world food supplier in 2045. This study aimed to evaluate land reserves for future agricultural development. Spatial analysis was conducted using land cover map, peatland distribution map, indicative map of suspension of new permits, forest status map, licensing map, and agricultural land use recommendation map. The land assumed to be potentially available should be (i) idle land covered by shrub as well as bare land, (ii) agronomically suitable for agriculture, (iii) within the designated area of non-forest uses (APL), conversion production forest (HPK), or production forest (HP), (iv) outside the moratorium area, and (v) outside the licensed area. Analysis results show that out of 29.8 million hectares of idle land, only about 7.9 million hectares are potentially available for future agricultural extensification. The available potential land area is much less than that required to meet the self-sufficiency target and to become the world food storage by 2045, i.e. of 5.3 million hectares for rice crop, shallot and sugar cane, and about 10.3 million hectares for upland rice, maize, soybean, peanut, mungbean, sugar cane, shallot, cassava, and sweet potato. Therefore, the main strategies to take are intensification of existing agricultural land and a strict control of agricultural land conversion.