[3] Pinus merkusii is a medium-sized to large tree, reaching 25–45 metres (82–148 feet) tall and with a trunk diameter of up to 1 m (3 ft 3 in).

The bark is orange-red, thick and deeply fissured at the base of the trunk, and thin and flaky in the upper crown.

Pinus merkusii is closely related to the Tenasserim pine (P. latteri), which occurs farther north in southeast Asia from Myanmar to Vietnam; some botanists treat the two as conspecific (under the name P. merkusii, which was described first), but P. latteri differs in longer (18–27 cm or 7–10+1⁄2 in) and stouter (over 1 mm thick) leaves and larger cones with thicker scales, the cones often remaining closed for some time after maturity.

Isolated populations of Pinus merkusii can be found in Mainland Southeast Asia, such as Kirirom National Park, on the Cardamom Mountains in Cambodia and Bidoup Núi Bà National Park on the Đà Lạt Plateau in Vietnam.

[4] The population in central Sumatra, between 1° 40' and 2° 06' S latitude, is the only natural occurrence of any member of the Pinaceae south of the Equator.