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

To use the air flow calculator, you simply need the volume air flow or air velocity (measured in ft/sec, ft/min, miles/hr (mph), or any other common units), the duct type or area (whether it's a rectangle duct or a circular duct), and the units you're using to measure. Then hit “calculate”, and our air flow rate calculator will do the rest.  

Online Duct Airflow Calculator

For an air flow pressure calculator, we need to look at 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 distance in LFM (ft/min, linear feet per minute). By using an air velocity 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 air flow velocity calculation, which measures the airflow per hour instead of per minute. 

Ready to use our CFM air flow velocity calculator? To calculate, enter the value, select the air velocity units that you prefer, and hit calculate. Then, our air 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)



Looking For HVAC Supplies?

Shop for HVAC spare parts, dampers, and controllers now at Blackhawk Supply store!


What Is Air Flow Rate?

Air flow, or airflow, at its most basic definition, refers to the movement of air, and the more distance it travels, the higher its rate. In the context of your heating and cooling system, using the right pipe 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 volume flowing past 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 CFM. With a CFM air flow velocity 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 the air flow rate? Let's get to the calculations. 

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

If you're wondering how to calculate air flow rate from pressure and diameter yourself, don't worry, because we're sharing the right equations to use if you're skipping the calculator for your at-home air flow calculation using pressure. 

The air flow calculation through the 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 (air flow 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 the air velocity rate in pipe systems. Knowing how to calculate airflow is the key to running an HVAC system smoothly, aiding in troubleshooting any issues that may arise.  


Still, struggling with how air velocity CFM in the pipe is measured? 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 velocity in duct systems for a perfectly operating heating and cooling unit. 

Free Shipping

Free Shipping On
Orders over $999*

Customer Satisfaction

Excellent Customer

Secure Payment

Secure Online

Customer Service

5-star Customer

Quantity Discounts


interested in partnerships?

Learn More →