The Pyramids and Temples of Gizeh by Sir Flinders Petrie - measure





9068.8 .5 inches = 755.69 - 755.78 ft.

(Egyptian Govt survey, 1925. 755.44 - 756.08 ft)

5776.0 7.0 inches = 480.75 - 481.92 ft.

(Egyptian Govt survey, 1925. 481.4 ft)

51 52' 2'

Observations with goniometer 51 48' - 51 57',

Casing stones "in situ", approx 51 45' - 51 49'

(Egyptian Govt survey. 1925. 51 52')

Ref 1 Ref 2




Square base seen as uneven. (Egyptian Govt survey, 1925). It might have been measured that way in 1925 but if we listen to Petrie who praises Khufu's "quality of workmanship", it is most unlikely that the square base on the pavement would have originally been finished as anything but true. The greatest difference between the 4 sides recorded by Petrie is the equivalent of about 46mm (East 9067.7, South 9069.5 inches).

The fact that Petrie could not get a better reading than 7.0 inches for height emphasizes the importance he attached to the missing outer casing, ie; the thicknesses for the individual missing blocks giving the true slope can only be guessed at. Over-riding the guess work can only be done if we settle for a slope as a continuation of the casing blocks in situ on the North side. (see below)

If Petrie slightly misread the true baseline or the true baseline level, as has often been suggested, then it is quite possible that the lesser angles offer the better estimate for the original slope :
ie : Casing stones in situ : North side. 51 45' - 51 49' (by theodolite).

Note :

The Great Pyramid has been in ruins for a very long time. When its outer casing either fell to the ground or was stripped by the Arabs all hope of recording its true dimensions ceased there and then. We really do not know its true baseline, hence its height and slope. At some time or other the pyramid was also hit by natural disasters (Petrie). A series of earthquakes would not seem an unreasonable assumption so our best estimates will now probably rely on the ability of future researchers to declare it a true geometric structure, one that responds to known proportions. This certainly poses a problem because a number of known proportions giving "more or less" similar results conveniently fall within the limits of the best recorded data : see "Theories compared with facts"


Descending passage

Ascending passage

26 31' 23" 5" ?

Lower part (up to Gallery) 26 02' 30"

Upper part (Gallery) 26 16' 40"

Mean of whole 26 12' 50"





With the ascending passage, we may well ask why the masons worked their way up to the beginning of the Gallery at approximately 26 02' but then changed it noticeably for the Gallery itself. Did the masons stop at the Gallery to re-calculate after some concern was raised about the angle of the newly laid floor ?. Would it have missed its mark at King's chamber height ?. Perhaps the angle of the Gallery floor was then readjusted to bring it back in line with the planned angle. Petrie's data "Mean of whole" 26 12' 50" may in fact reflect the planned angle closer than we think. This being the case we still have two different angles to contend with, the ascending angle about a 1/3 of a degree less than the descending. The question is ... why were the two angle planned this way and what was behind their geometry ? Of course if the descending passageway wasn't honed with incredible accuracy (a consistent altitude) we might not be asking these questions.

At the Trial Site East of the Great pyramid where the masons experimented with design the passageway angles reflect the same 1/3 of a degree difference.

Comments welcome

True scale : If drawing the Great pyramid to scale Section 64 is to be consulted for it has all the necessary measurement to correctly place the passageways and chambers.


Royal cubit ... Base of King's chamber ... 20.632 .004 inches (523.95 - 524.15mm)
Royal cubit ... Summarized Pyramid ...... 20.620 .005 inches (523.62 - 523.87mm)
Digit (unit named by Petrie) ... .727 .002 inches (18.41 - 18.52mm)

Note : The royal cubit standard agreed upon for the 4th dynasty is generally quoted as the second measure, ie; 20.620 .005 inches although as you can see there is but 1/3rd of a millimetre difference between them. The digit, so named by Petrie, is mainly from the 4th dynasty tombs he examined and it is consistently accurate to within 1/10th of a millimetre. Although some might disagree on the way he presented this data it is by far the best indication we have for metrological proficiency during this period.




Related information :

Khufu, the unfinished Pyramid

Last Updated: June 6th, 2011