Online Air Velocity and Airflow Rate Calculator

Wondering how to calculate air flow velocity? Blackhawk Supply offers a convenient air velocity calculator online, allowing you to convert the various units for volume air flow and air velocity flowing through your system. With this calculator, we make it easy to learn how to calculate airflow in CFM with a convenient duct airflow calculator. 

To use the air flow calculator, you simply need the volume air flow or air velocity, the duct type or area, and the units you’re using to measure. Then hit “calculate,” and our air flow rate calculator will do the rest. 

What is Air Flow Rate?

Air flow, or airflow, at its most basic definition, refers to the movement of air. In the context of your heating and cooling system, using the right air flow calculation formula will help guarantee that your system runs effectively. 

Why is it important to know how to calculate air flow for HVAC? Well, if you have too much air flowing through the system, you may notice more humidity in your space. On the other hand, if air flow is too low, your coils may get icy and flood your air compressor - and we certainly don’t want that. However, using a simple online air flow calculator, you can find how to calculate air flow through pipe systems for the right airflow rate to keep your system running.

When it comes to something like an HVAC air flow calculation formula, we are looking to measure the air that passes the evaporator coil. This passing air is measured in cubic feet per minute (CFM). With a CFM air flow calculator, we want to ensure that around 350 to 400 CFM per ton of cooling is being used, as this ensures the air conditioning system will run properly. 

So, how do you calculate air flow rate? Let’s get to the calculations. 

Online Air Flow Calculator

When it comes to an air flow pressure calculator, we are looking at the air velocity. Air velocity is the distance traveled per minute and is used as a measurement of the displacement rate for air and gas. 

An air velocity calculator will express this in LFM, or linear feet per minute. By using an air flow through duct calculator, you’re multiplying the air velocity by the area of a duct. With this, you’ll find the air volume that flows past the duct in terms of units per time. This measurement is typically represented in CFM, but with an airflow calculation conversion, you can find a CMH airflow calculation, which measures the airflow per hour instead of per minute. 

Ready to use our air flow velocity calculator? To calculate, enter the value, select what unit you prefer, and hit calculate. Then, our airflow volume calculator will do the work and display your results below.

Enter Your Values:

H: W:

ft/min (LFM)


miles/hr (MPH)

ft3/min (CFM)



How Do You Calculate Air Flow Rate (Air Flow Calculation Formula)?

If you’re wondering how to calculate air flow rate from pressure and diameter, we are sharing the equation to use in case you’re skipping the calculator for your at-home air flow calculation using pressure. 

The air flow calculation through pipe equation is represented as:

In this air flow calculation formula, the values are represented as “d” (pipe inner diameter in inches), “v” (air velocity ft/s), and Qa (airflow rate in CFM). 

Being aware of how to calculate airflow through a pipe is key to running your system properly. For many, this can be a challenging calculation, and the HVAC duct flow calculation isn’t taught to all technicians. However, knowing how to calculate airflow through a duct can lend a hand in figuring out any issues that may arise with your air conditioning system. 

No more wondering, “how do you calculate air velocity” with our formula to calculate air flow rate in pipe systems. Knowing how to calculate air flow is the key to running an HVAC system smoothly, aiding in troubleshooting any issues that may arise. 


Still struggling with how to calculate air velocity? No worries, our team at Blackhawk Supply can help. Contact us at (847) 773-0645 and our specialists will answer all your questions about how to calculate air flow in duct systems for a perfectly operating heating and cooling unit. 

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