Pressure Unit Conversion
Pressure, the effect of a force applied to a surface, is a derived unit. The unit of pressure in the SI system is the pascal (Pa), defined as the force of one newton per square meter:
1Pa = 1 N/cm2
In chemistry, it is more common to express pressures in units of atmospheres or torr:
1 atm = 101325 Pa = 760 torr ~ 760 mm Hg
Torr and millimeters of mercury (mm Hg, defined as a one millimeter difference in the height of a mercury barometer at 0°C) are nearly equivalent. Another unit of pressure used in meteorology is the bar:
1 bar = 105 N/m2 = 750.06 torr = 0.987 atm.