Enter the volume air flow rate and the face area into the calculator to determine the face velocity. This calculate can also evaluate the air flow or area given the other variables.

Face Velocity Formula

The following equation is used to calculate the Face Velocity.

FV = AF / FA
  • Where FV is the face velocity (ft/s)
  • AF is the air flow rate (ft^3/s)
  • FA is the face area (ft^2)

To calculate the face velocity, divide the volume flow rate by the face area.

What is a Face Velocity?


A face velocity is a measure of the speed of the air moving through the inlet or outlet of an HVAC system.

How to Calculate Face Velocity?

Example Problem:

The following example outlines the steps and information needed to calculate Face Velocity.

First, determine the face area. In this example, the face area is found to be 5 ft^2.

Next, determine the air flow rate. For this problem, the air flow rate is 75 ft^3/s.

Finally, calculate the Face Velocity using the formula above:

FV = AF * FA

FV = 75 / 5

FV = 15 ft/s