For an Association football, 8-12 psi. For an American football, 12.5-13.5 psi. For an Australian football, 9-11 psi.
Regulation
9.0-11.0 psi - [Ref. "Football (ball)" - Wikipedia]
The word regulation is an adjective as well as a noun (regulation football, regulation uniform, etc). Regulatory is another adjective form for the noun regulation.
2
Heavy as needed
The size of the regulation college football field.
The weakness in football is if you concentrate on the ball and where your players are standing then you get to score a goal and you have fun
Footballs are usually inflated to 13 psi. I've seen junior footballs that were supposed to be inflated to 7.
The pressure inside a football is caused by the air particles inside the ball being compressed by the addition of increasing amounts of air. The standard PSI of a professional football is 13 psi (Pounds per square inch).
13 psi
Footballs are inflated to 13 pounds per square inch (psi).