How big is K2?
K2: 8,611 m (28,251 ft). Measured as elevation — summit elevation above sea level.
Source: Wikipedia — K2
Where it sits
Among the 10 mountains on this page K2 ranks 2nd from the top by size. The largest in the group is Mount Everest at 8,848.86 m, which is 1.03× the size of K2, while the smallest, Ben Nevis, is 1,345 m.
Stand an adult of 1.7 m beside it and the ratio is 5,065×: you would need 5,065 people stacked head to foot to match its size — roughly a crowd the size of a small town standing on each other.
In everyday distances
A football pitch is about 105 m long. K2 is 82× that, which puts it at 82 pitch lengths from end to end.
Climbing is about vertical metres, not horizontal ones: 8,611 m of elevation is 2,870 storeys of a typical 3 m floor. Even a lift moving at 10 m/s would need 14 minutes to cover it.
Next to its neighbours in size
The nearest thing larger than it in this collection is Mount Everest at 8,848.86 m (29,032 ft), 1.03× the size. Both figures are the same kind of measurement, so the gap is a fair one.
The nearest thing smaller is Kangchenjunga at 8,586 m (28,169 ft), so K2 is 1× as big as it. They sit in the same group.
Against fixed yardsticks
Against three fixed yardsticks — K2 is 26.1× the size of Eiffel Tower (330 m); K2 is 288× the size of blue whale (29.9 m); Earth (12,742 km) is 1,480× the size of K2.
How this figure was taken
Elevation is measured from mean sea level to the summit, not from the base of the mountain. Surveys are revised, so a figure here can differ from an older atlas by a few metres.
How the sizes are taken. Each figure says what it measures — height, length, diameter or elevation — and for which individual or convention. Everything is drawn standing upright on one baseline so a single scale holds, including things that are long rather than tall. Values come from the linked Wikipedia article for each item.
Read the rest — common questions
How big is K2?
8,611 m (28,251 ft), measured as elevation: summit elevation above sea level.
Where does K2 rank among mountains?
Number 2 of 10 on this site, from Mount Everest at 8,848.86 m down to Ben Nevis at 1,345 m.
What is the next size up?
Mount Everest, at 8,848.86 m, is 1.03× the size.
What is the next size down?
Kangchenjunga, at 8,586 m, is 1× smaller.
How reliable is the figure?
It is taken from the cited Wikipedia article and states its basis (summit elevation above sea level). Values are rounded, and where individuals differ the figure is a representative one, so expect small differences from other sources.