The area of Lebanon is around 10,452 square kilometers. The nation is roughly rectangular in shape, becoming narrower toward the south and the farthest north. Its widest point is 88 kilometers, and its narrowest is 32 kilometers; the average width is about 56 kilometers. The physical geography of Lebanon is determined by natural systems that extend outside the nation. Thus, the Biqa Valley is part of the Great Rift system, which stretches from southern Turkey to Mozambique in Africa. Like any mountainous nation, Lebanon's physical geography is complex. Land forms, climate, soils, and vegetation differ markedly within short distances. There are also sharp changes in other elements of the environment, from good to poor soils, as one moves through the Lebanese mountains.

Emerging from a base south of Homs in Syria, the eastern mountain range, or Anti-Lebanon is almost equal in length and height to the Lebanon Mountains. This geographical region falls swiftly from Mount Hermon to the Hawran Plateau, whence it continues through Jordan south to the Dead Sea. The Barada gorge divides Anti-Lebanon. In the northern section, few villages are on the western slopes, but in the southern section, featuring Mount Hermon -286 meters, the western slopes have many villages. Anti-Lebanon is more arid, particularly in its northern parts, than Mount Lebanon and is accordingly less productive and more thinly populated.