Ulu Kalumpang Forest Reserve is a region in Sabah, Malaysia.

Located on the Tawau Peninsula, it was designated as a conservation area by the Sabah Forestry Department in 1992.

The forest reserve is in an area called the Tawau Highlands, which also includes Tawau Hills National Park.

A statewide orang-utan census carried out by HUTAN (an NGO based in Sukau, Kinabatangan) and the Sabah Wildlife Department estimated an Orang-utan population density of 0.42 individual/km² within the forest reserve.

This orang-utan population of ~ 183 individuals is totally isolated and its long-term survival is insecure.