The Dimensions of the Giza Site Plan
  From the Results of the Survey carried out by W.M.F. Petrie.

Using some of the finest surveying equipment available in his day, 
W.M. Flinders Petrie determined the exact dimensions and relative 
positions the Giza Pyramids using an extensive triangulation - the 
main stations of which were stated to have been established with an 
accuracy of 0.1 inch.  That Petrie in fact achieved a high degree 
of precision was confirmed in 1925, when the most meticulous survey 
of the Great Pyramid was carried out by J.H. Cole for the Survey 
Department of the Egyptian Government.  The result for the mean side 
of the Great Pyramid differed from Petrie's value by only 0.6 inch - 
a remarkably close agreement, considering the size of the monument 
and the destruction of most of the outer casing.

The following are the Mean Sides of Base of the three Giza Pyramids, 
as stated by Petrie in inches, and here converted into royal cubits 
using the value of 20.620 inches (0.52375 metres):

                     Inches  +/-   Azimuth    Cubits   Design   
    Great  Pyramid   9068.8  O.6   -3' 43"    439.81   439.82  
    Second    "      8474.9  1.5   -5' 26"    411.00   411.00    
    Third     "      4153.6  3.0  +14' 03"    201.44   201.50 
                                                                
Petrie believed that the sides of the Great Pyramid could have been 
adjusted so as to express the 'pi-proportion' more accurately than 
the value for pi of 22/7, which would have given a side-length of 
just 440 cubits for the height of 280 cubits.  Hence the 'design' 
length of side becomes 280 * (pi)/2 = 439.82... cubits.

The following are the Axial Distances in inches that separate the 
centres of the three Pyramids, as calculated by Petrie along axes 
constructed at the mean azimuth of the Second and Great Pyramids:

                                             N to S     E to W  
   Centre of 1st to Centre of 2nd Pyramid    13931.6    13165.8  
   Centre of 2nd to Centre of 3rd Pyramid    15170.4     9450.2  
   Centre of 1st to Centre of 3rd pyramid    29102.0    22616.0  

From the above survey-data, we can now compute the major components 
of spacing between the sides of the three Pyramids, as follows:

               Axial Distances from North to South
                                      Inches    Cubits    Design
   N side 1st to S side 2nd Pyramid   22703.4   1101.04   1101
   S   "  2nd to S  "   3rd    "      13009.7    630.93    631
   N   "  1st to S  "   3rd    "      35713.2   1731.97   1732
   S   "  1st to N  "   2nd    "       5159.7    250.23    250
   S   "  2nd to N  "   3rd    "       8856.1    429.49    429.5

                Axial Distances from East to West
                                      Inches    Cubits    Design
   W side 1st to W side 2nd Pyramid   12868.8    624.09    624 
   W   "  2nd to W  "   3rd    "       7289.5    353.52    353.5
   E   "  1st to W  "   3rd    "      29227.2   1417.42   1417.5
   W   "  1st to E  "   2nd    "       4393.9    213.09    213  
   W   "  2nd to E  "   3rd    "       3135.9    152.08    152  

As shown by the above results, the mean components of spacing along 
the axes of the ground plan differ on average from their respective 
'design' values, by about 0.07 cubit or 1.5 inches.

Surprisingly, Petrie did not calculate the distances between the 
three pyramids in terms of the Egyptian royal cubit, and concluded 
that no exact relation existed between the positions of the bases.

                                              John Legon, June 1996

                        References

W.M.F. Petrie, The Pyramids and Temples of Gizeh (London, 1883).
J.A.R. Legon,  'A Ground Plan at Giza', Discussions in Egyptology, 
               Vol. 10 (1988), 33-40.
J.A.R. Legon,  'The Giza Ground Plan and Sphinx', Discussions in 
               Egyptology, Vol. 14 (1989), 53-8.