K2 lies in the northwestern Karakoram Range. It is located in the Baltistan region of Gilgit–Baltistan, Pakistan and the Taxkorgan Tajik Autonomous County of Xinjiang, China. The Tarim sedimentary basin borders the range on the north and the Lesser Himalayas on the south. Melt waters from vast glaciers, such as those south and east of K2, feed agriculture in the valleys and contribute significantly to the regional fresh-water supply.
K2 is merely ranked 22nd by topographic prominence, a measure of a mountain's independent stature, because it is part of the same extended area of uplift (including the Karakoram, the Tibetan Plateau, and the Himalaya) as Mount Everest, in that it is possible to follow a path from K2 to Everest that goes no lower than 4,594 metres (15,072 ft), at Mustang Lo. Many other peaks, that are far lower than K2, are more independent in this sense. It is, however, the most prominent peak within the Karakoram range.
K2 is notable for its local relief as well as its total height. It stands over 3,000 metres (9,840 ft) above much of the glacial valley bottoms at its base. It is a consistently steep pyramid, dropping quickly in almost all directions. The north side is the steepest: there it rises over 3,200 metres (10,500 ft) above the K2 (Qogir) Glacier in only 3,000 metres (9,800 ft) of horizontal distance. In most directions, it achieves over 2,800 metres (9,200 ft) of vertical relief in less than 4,000 metres (13,000 ft).
A 1986 expedition led by George Wallerstein made an inaccurate measurement incorrectly showing that K2 was taller than Mount Everest, and therefore the tallest mountain in the world. A corrected measurement was made in 1987, but by that point the claim that K2 was the tallest mountain in the world had already made it into many news reports and reference works.