Enter the internal and external pressure and the total surface area into the calculator to determine the force from the pressure gradient.

Pressure Gradient Force Formula

The following equation is used to calculate the force from the pressure gradient.

F = |IP – EP| * A

  • Where F is the force (lb-f)
  • IP is the internal pressure (psi)
  • EP is the external pressure (psi)
  • A is the surface area

What is a Pressure Gradient Force?


The pressure gradient force is a force that exists as a result of pressure differences in a fluid. It is responsible for the acceleration of the fluid and can be described as the change in pressure with distance.

The pressure gradient force is the force that causes a parcel of air to accelerate as it flows from an area of high pressure to a place of low pressure. It is caused by the fact that molecules are forced together more tightly in high-pressure areas than in low-pressure areas.

How to Calculate Pressure Gradient Force?

Example Problem:

The following example outlines the steps and information needed to calculate the Pressure Gradient Force.

First, determine the internal pressure. For this example problem, the internal pressure is measured to be 50 psi.

Next, determine the external pressure. In this case, the external pressure is 25 psi.

Next, determine the total surface area the pressure differential is acting on. For this problem, the area is 5 square inches.

Finally, calculate the pressure gradient force using the formula above:

F = |IP – EP| * A

F = |50- 25| *5

F = 125 lb-f