According to Petrie the mean height of the narrow South Subtteranean passageway that leads to a dead end is 717 mm. It's base on average is 30.886 m (avg of 1219" 1213") below the base of the pyramid. The 30.886 m length is more or less the width of the Parthenon at the stylobate.

Balanos measured the Eastern side at 30.87 m and the Western side at 30.88 m. He also measured the "Meridian" part of the temple taking the position of the statue of the goddess as the center. The outcome was 30.893 meters. Wikipedia has the width at 30.9 meters.

The theoretic width can be derived from the mean volumetric radius of the Earth. We consider a circle having a radius equal the mean volumetric radius of the Earth. We then compute the length of one arc second of this circle:

C = 2 x π x (6,371,000.8 m) = C/360/60/60 = 30.8875 meters

Athanasios Aggelopoulos in his book(in Hellenic) "Metron Ariston" presents the width of the step of the Parthenon that leads to the stylobate as he measured it in various part. This width ranges from 693.5 mm to 703.5 mm. This agrees with the height of the South Subterranean passage which according to Petrie ranges from 660 to 744 mm. One of his three readings(the middle on) on the West side is at 686 mm. This is a picture I have taken from the Parthenon showing the steps:



The theoretic relationship between the length, the width and the height of the Parthenon is based on the ratio 9:4. The height to length ratio is thus 16/81. The 81 number is the isopsephy value of Kadmeia:

KADMEIA = 20+1+4+40+5+10+1 = 81