The pounds per square inch (PSI) also termed as pound-force per square inch, a unit of pressure. It is the pressure which can be resulted from a force of one pound-force applied to an area of one square inch. Use this online Aviation Pounds Per Square Inch Calculator to calculate its PSI based on its head value and specific gravity. Gravity can produce pressure in a fluid but the magnitude of the pressure depends on the sort of substance the fluid comprises.
A liquid container has specific gravity of 12 and head value of 25.
c = (a x b) / 2.31
= (25 x 12) / 2.31