How big is Burj Khalifa?
Burj Khalifa: 828 m (2,717 ft). Measured as height — architectural height.
Source: Wikipedia — Burj Khalifa
Where it sits
Among the 23 buildings & towers on this page Burj Khalifa ranks 1st from the top by size. Nothing else in its group is bigger here, and the smallest, Christ the Redeemer at 30 m, is 27.6× smaller.
Stand an adult of 1.7 m beside it and the ratio is 487×: you would need 487 people stacked head to foot to match its size.
In everyday distances
A football pitch is about 105 m long. Burj Khalifa is 7.89× that, which puts it at 7.9 pitch lengths from end to end.
Walking at an easy 1.4 m/s you cover 828 m in 9.9 minutes. A jet at 900 km/h covers it in 3.3 seconds.
Next to its neighbours in size
The nearest thing larger than it in this collection is Ben Nevis at 1,345 m (4,413 ft), 1.62× the size. Note the two figures are not the same measurement: for Burj Khalifa it is height, for Ben Nevis it is elevation.
The nearest thing smaller is Tokyo Skytree at 634 m (2,080 ft), so Burj Khalifa is 1.31× as big as it. They sit in the same group.
Against fixed yardsticks
Against three fixed yardsticks — Burj Khalifa is 2.51× the size of Eiffel Tower (330 m); Burj Khalifa is 27.7× the size of blue whale (29.9 m); Earth (12,742 km) is 15,389× the size of Burj Khalifa.
How this figure was taken
Building heights depend on the rule used: architectural height counts spires but not antennas, tip height counts everything. The basis is named with each figure.
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 the Burj Khalifa?
828 m (2,717 ft), measured as height: architectural height.
Where does the Burj Khalifa rank among buildings & towers?
Number 1 of 23 on this site, from Burj Khalifa at 828 m down to Christ the Redeemer at 30 m.
What is the next size up?
Ben Nevis, at 1,345 m, is 1.62× the size.
What is the next size down?
Tokyo Skytree, at 634 m, is 1.31× smaller.
How reliable is the figure?
It is taken from the cited Wikipedia article and states its basis (architectural height). Values are rounded, and where individuals differ the figure is a representative one, so expect small differences from other sources.