Calculate vacuum pressure or absolute pressure from local atmospheric pressure and one known pressure value in Pa, bar, psi, and more.

Vacuum Pressure Calculator

Enter local atmospheric pressure and one known pressure value.

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Vacuum Pressure Formula

The following formula is used to calculate the Vacuum Pressure. 

Pvac = PL - PA
  • Where Pvac is the Vacuum Pressure (Pa)
  • PL is the local atmospheric pressure (Pa) 
  • PA is the absolute pressure (Pa) 

To calculate a vacuum pressure, simply subtract the absolute pressure from the local atmospheric pressure.

How to Calculate Vacuum Pressure?

The following two example problems outline how to calculate the Vacuum Pressure.

Example Problem #1:

  1. First, determine the local atmospheric pressure (Pa). In this example, the local atmospheric pressure (Pa) is given as 500.
  2. Next, determine the absolute pressure (Pa). For this problem, the absolute pressure (Pa) is given as 400.
  3. Finally, calculate the Vacuum Pressure using the equation above: 

Pvacuum = PL – PA

Inserting the values from above and solving the equation: 

Pvacuum = 500 – 400 = 100 (Pa)

Example Problem #2: 

Using the same process as above, first define the variables required by the formula. In this case, these values are:

local atmospheric pressure (Pa) = 234

absolute pressure (Pa) = 95

Entering these values yields:

Pvacuum = 234 – 95 = 139 (Pa)