It is referred to as pounds per square inch (gauge) or PSIG. The electrical output of a gauge pressure transducer is 0 VDC at 0 PSIG ( PSIA) and full scale output (typically 5 VDC) at full scale pressure (in PSIG). Absolute pressure is measured relative to high vacuum (0 PSIA). It is referred to as pounds per square inch (absolute) or PSIA.