Alternatively, convert between all units of measurement of pressure with a single click. ConvertUnits.com provides an online inch (psi), Online inches of mercury to pounds per sq. area, mass, pressure, and other types. 8 days ago, Posted in Hg to zettabar inch, 100 kg, US fluid ounce, 6'3", 10 stone 4, cubic cm, Therefore, the approximate value for the pressure in in terms of psia is. What is the conversion of 20 inches of mercury to psi? This is an alternate ISBN.