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Vacuum Pressure Units Conversion Calculator

Fluids Systems Design and Engineering

Vacuum Pressure Units Conversion From Torr to Various Units Calculator

On the dials of most pressure gauges, atmospheric pressure is assigned the value of zero. Vacuum measurements must have a value of less than zero. Negative gauge pressure is the difference between the system vacuum pressure and atmospheric pressure. Absolute pressure is the pressure (in psia) above a perfect vacuum and is equal to atmospheric pressure less negative gauge pressure.

Other vacuum units are atmospheres, torr, and micrometers. To calculate atmospheres, divide absolute pressure in psia by 14.7. A torr is 1/760 of an atmosphere, and a micrometer is 0.001 torr.


Pressure Torr Equivalent
0.0010 torr = 1 micrometer of mercury (µm Hg)
0.0075 torr = 1 pascal (Pa)
0.7501 torr = 1 millibar (mbar)
1.000 torr = 1 mm mercury (mm Hg)
1.868 torr = 1 in. water at 4°C (in. H2O)
25.40 torr = 1 in. mercury (in. Hg)
51.71 torr = 1 lb/in2 (psi)
735.6 torr = 1 tech. atmosphere (at)
750.1 torr = 1 bar
760.0 torr = 1 standard atmosphere (atm)

Vacuum Pressure Units Conversion Graphic

Reference: ASPE