Calculate vacuum pressure, absolute pressure, or gauge pressure from atmospheric pressure and a vacuum reading. Convert vacuum pressure in PSI, kPa, bar, MPa, Pa, inHg vacuum, mmHg vacuum, torr, and microns.
Atmospheric pressure:
Enter local atmospheric pressure. Standard sea-level pressure is about 14.696 PSI or 29.92 inHg.
Vacuum reading:
Enter the vacuum amount below atmosphere, or enter an absolute pressure reading such as microns or torr.
Result:
The calculator shows vacuum pressure, absolute pressure, and negative gauge pressure in common vacuum units.
A vacuum pressure calculator is useful for HVAC evacuation, vacuum pumps, lab systems, engines, tanks, suction systems, process equipment, vacuum gauges, and converting between inHg vacuum, PSIA, torr, and microns.
This calculator is for pressure conversion and estimates. Real vacuum systems can be affected by leaks, pump capacity, hose restrictions, temperature, moisture, and gauge accuracy.
The basic vacuum pressure relationship is:
Absolute Pressure = Atmospheric Pressure - Vacuum Pressure
Gauge pressure below atmosphere can also be written as:
Gauge Pressure = Absolute Pressure - Atmospheric Pressure
Vacuum pressure is pressure below atmospheric pressure. It is often shown as inches of mercury vacuum, PSI vacuum, or negative gauge pressure.
Subtract the vacuum pressure from atmospheric pressure. Absolute pressure equals atmospheric pressure minus vacuum pressure.
At standard sea-level pressure, full vacuum is about 29.92 inHg vacuum. At different atmospheric pressure, the maximum inHg vacuum changes.
Microns usually refer to microns of mercury absolute. Lower micron values mean deeper vacuum.