How big is Great Pyramid of Giza?
Great Pyramid of Giza: 139 m (454 ft). Measured as height — its current height (146.6 m when built).
Source: Wikipedia — Great Pyramid of Giza
Where it sits
Among the 23 buildings & towers on this page Great Pyramid of Giza ranks 19th from the top by size. The largest in the group is Burj Khalifa at 828 m, which is 5.98× the size of Great Pyramid of Giza, while the smallest, Christ the Redeemer, is 30 m.
Stand an adult of 1.7 m beside it and the ratio is 81.5×: you would need 81 people stacked head to foot to match its size.
In everyday distances
A football pitch is about 105 m long. Great Pyramid of Giza is 1.32× that, which puts it at 1.3 pitch lengths from end to end.
Walking at an easy 1.4 m/s you cover 139 m in 1.6 minutes. A jet at 900 km/h covers it in 554 milliseconds.
Next to its neighbours in size
The nearest thing larger than it in this collection is Washington Monument at 169 m (554 ft), 1.22× the size. Both figures are the same kind of measurement, so the gap is a fair one.
The nearest thing smaller is Saturn V at 111 m (363 ft), so Great Pyramid of Giza is 1.25× as big as it. They come from different groups — vehicles & ships against buildings & towers — which is what makes the pairing interesting.
Against fixed yardsticks
Against three fixed yardsticks — Eiffel Tower (330 m) is 2.38× the size of Great Pyramid of Giza; Great Pyramid of Giza is 4.63× the size of blue whale (29.9 m); Earth (12,742 km) is 92,000× the size of Great Pyramid of Giza.
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 Great Pyramid of Giza?
139 m (454 ft), measured as height: its current height (146.6 m when built).
Where does the Great Pyramid of Giza rank among buildings & towers?
Number 19 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?
Washington Monument, at 169 m, is 1.22× the size.
What is the next size down?
Saturn V, at 111 m, is 1.25× smaller.
How reliable is the figure?
It is taken from the cited Wikipedia article and states its basis (its current height (146.6 m when built)). Values are rounded, and where individuals differ the figure is a representative one, so expect small differences from other sources.