The average professional heavy weight boxer hits at between 1,200 to 1,700 pounds per square inch, or psi. Legendary boxer Mike Tyson had a punch that was measured at 1,800 psi, or almost one ton of force per square inch.
Pounds per square inch is usually measured using pressure gauges, but for boxing measurements, special machines are used. These machines calculate how hard a punch is by measuring the power of the punch at impact, calculating the size of the impact zone, and converting that to psi. So if a punch is 1,500 psi and covers four square inches of space, it is the equivalent of 6,000 pounds of impact.