Around 1,100 pounds.
An article published by The Washington Post titled as No, you can’t crush a man’s skull with your bare hands, reports the human skull can withstand 6.5 GPa of pressure.
It is the pressure resulting from a one pound-force applied to an area of one square inch.
To fracture the skull would require 500 kgf, or the force that 500 kilograms (1,100 pounds) would exert in standard gravity.
In skull news, a study suggests the human skull evolved from fighting. Researchers at the University of Utah says H0mo sapiens’ ancestors evolved to take a punch to the face. Read more at Utah Public Radio