Pressure Calculator Enter a numerical starting value in the leftmost text box, and specify units. Select target units from the rightmost list, and click "calculate." Convert psi atmosphere kg/cm2 Torr inches Hg kPa Bar Metres H20 Head to psi atmosphere kg/cm2 Torr inches Hg kPa Bar Metres H20 Head Calculated results display here.

Absolute V. Gauge Pressure The difference between absolute pressure and gauge pressure is atmospheric pressure. A perfect vacuum has zero pressure. Absolute pressure is the pressure difference between the pressure you are measuring and a perfect vacuum. Gauge pressure is the pressure difference between the pressure you are measuring and atmospheric pressure. To convert a gauge pressure to absolute pressure, add the current value of the atmospheric pressure to the measured gauge pressure. If your gauge reading is -5 PSIG and your current atmospheric pressure is 15 PSIA then the absolute pressure you are measuring is 15+(-5) = 10 PSIA.