Gauge Pressure, Atmospheric Pressure, Negative Pressure and Absolute Pressure

Relation of Gauge Pressure, Atmospheric Pressure, Negative Pressure and Absolute Pressure:
Absolute Pressure = Atmospheric Pressure + Gauge Pressure
Gauge Pressure = Absolute Pressure - Atmospheric Pressure
Negative/ Vacuum Pressure = Atmospheric Pressure - Absolute Pressure
Pressure can be expressed as
Bar, Kgf/cm2/ Pa, Mpa, mm Hg, cm Hg, mH2O, m Hg, psi