[1] The commune covers an area of 820 square kilometres (320 sq mi).

[3] Lahmar lies at an altitude of 939 metres (3,081 ft) on a rocky plain with scattered higher mountains to the east.

One prominent range of hills is just to the east, and separates Lahmar from the nearby locality of Sfissifa.

[12] A local road leads to the provincial capital of Béchar, 30 kilometres (19 mi) to the south.

[18] Lahmar has a polyclinic, a room care facility and a maternity ward.