Nepal is of roughly trapezoidal shape, 800 kilometres (497 mi) long and 200 kilometres (124 mi) wide, with an area of 147,181 km2 (56,827 sq mi). See List of territories by size for the comparative size of Nepal. It lies between latitudes 26° and 31°N, and longitudes 80° and 89°E.
Nepal is commonly divided into three physiographic areas: Mountain, Hill and Terai. These ecological belts run east–west and are vertically intersected by Nepal's major, north to south flowing river systems.
The southern lowland plains or Terai bordering India are part of the northern rim of the Indo-Gangetic Plain. They were formed and are fed by three major Himalayan rivers: the Kosi, the Narayani, and the Karnali as well as smaller rivers rising below the permanent snowline. This region has a subtropical to tropical climate. The outermost range of foothills called Sivalik Hills or Churia Range cresting at 700 to 1,000 metres (2,297 to 3,281 ft) marks the limit of the Gangetic Plain, however broad, low valleys called Inner Tarai Valleys (Bhitri Tarai Uptyaka) lie north of these foothills in several places.
The Hill Region (Pahad) abuts the mountains and varies from 800 to 4,000 metres (2,625 to 13,123 ft) in altitude with progression from subtropical climates below 1,200 metres (3,937 ft) to alpine climates above 3,600 metres (11,811 ft). The Lower Himalayan Range reaching 1,500 to 3,000 metres (4,921 to 9,843 ft) is the southern limit of this region, with subtropical river valleys and "hills" alternating to the north of this range. Population density is high in valleys but notably less above 2,000 metres (6,562 ft) and very low above 2,500 metres (8,202 ft) where snow occasionally falls in winter.
The Mountain Region (Himal), situated in the Great Himalayan Range, makes up the northern part of Nepal. It contains the highest elevations in the world including 8,848 metres (29,029 ft) height Mount Everest (Sagarmāthā in Nepali) on the border with China. Seven other of the world's "eight-thousanders" are in Nepal or on its border with China: Lhotse, Makalu, Cho Oyu, Kangchenjunga, Dhaulagiri, Annapurna and Manaslu.
Nepal has five climatic zones, broadly corresponding to the altitudes. The tropical and subtropical zones lie below 1,200 metres (3,937 ft), the temperate zone 1,200 to 2,400 metres (3,937 to 7,874 ft), the cold zone 2,400 to 3,600 metres (7,874 to 11,811 ft), the subarctic zone 3,600 to 4,400 metres (11,811 to 14,436 ft), and the Arctic zone above 4,400 metres (14,436 ft).
Nepal experiences five seasons: summer, monsoon, autumn, winter and spring. The Himalaya blocks cold winds from Central Asia in the winter and forms the northern limit of the monsoon wind patterns. In a land once thickly forested, deforestation is a major problem in all regions, with resulting erosion and degradation of ecosystems.
Nepal is popular for mountaineering, having some of the highest and most challenging mountains in the world, including Mount Everest. Technically, the south-east ridge on the Nepali side of the mountain is easier to climb; so, most climbers prefer to trek to Everest through Nepal.