The Great Pyramid of Giza The Great Pyramid was built around 2600 BC and was the tallest structure in the world for nearly 4,000 years. It consists of about 2.3 million blocks weighing between 6 and 7 million tons. How many people did it take to build the Great Pyramid? Vaclav Smil in The numbers don’t lie gives an interesting calculation method:
The potential energy of the Great Pyramid (what is required to lift the mass above ground level) is about 2.4 trillion joules. The math is pretty simple: it is simply the product of the acceleration due to gravity, the mass of the pyramid, and its center of mass (one-quarter of its height)… I assume an average of 2.6 tons per cubic meter and therefore a total mass of about 6.75 million tons.
People are able to convert about 20 percent of food energy into useful work, which is equivalent to about 440 kilojoules per day for hard-working men. Quarrying the stones would therefore require about 5.5 million working days (2.4 trillion/44,000), or about 275,000 days per year over a 20-year period, and about 900 people could do it working 10 hours a day for 300 days a year. A similar number might be needed to set the stones in the rising structure and then smooth the revetment blocks… And to cut 2.6 million cubic meters of stone over 20 years, the project would have required about 1,500 quarrymen working 300 days a year and producing 0.25 cubic meters of stone per capita… the grand total would then be about 3,300 workers. Even if we were to double that number to account for designers, organizers, supervisors, etc., the total would still be less than 7,000 workers.
…At the time of the pyramid’s construction, the total population of Egypt was 1.5 to 1.6 million people, and therefore a deployed force of less than 10,000 men would not have represented an extraordinary burden on the country’s economy.
I was surprised by the low number and delighted by the unusual calculation method. Archaeological evidence from the nearby workers’ village He proposes 4,000 to 5,000 workers on the site, not counting quarrymen, haulers, designers and support staff. Smil’s calculation therefore seems very good.
What other unusual calculations do you know?
