Improving Indoor Air Quality
March 26, 2020

How to calculate CFM, match fan to filter to space and other FAQ’s…

What is CFM? (Cubic Feet per Minute)

CFM is a unit of volumetric capacity. It is commonly used by manufacturers of fans, blowers and filters. This is Cubic Feet per Minute.


How do I calculate CFM and determine the proper matching of fan to filter to space?

The proper matching of fan to filter to space. You need to calculate your room cubic feet, L’ x W’ x H’. After you have your total cubic foot, divide by either 1, 2, 3, 4 or 5. The more contaminants, heat and odor in the room, the lower the number you want to pick. This will be how many times you want to exchange the air in your room in minutes. 

CFM (Cubic Feet per Minute)

So if you have a 12′ x 12′ x 12′ room that is 1,728 cu.ft. An air exchange every minute you would need a 1,728 cfm fan and filter, every 2 minutes would be 864 cfm fan and filter, every 3 minutes would be 576 cfm, every 4 minutes would be 432 cfm fan and filter and every 5 minutes would be 345.6 cfm fan and filter. 

You will notice the higher CFM numbers on Air Boxes: *

*These are maximum numbers.

These are made to work perfectly with our in-line fans. So the CFM ranges are: 

  • AirBox 1- 175-500 cfm
  • AirBox 2- 435-1000 cfm
  • AirBox 3- 745-1500 cfm
  • AirBox 4- 785-2000 cfm
  • AirBox 4+ 1075-3500 cfm

**You can add a larger fan to the larger Air Boxes and still have “room” to do so. Like a Commercial Blower at either 2800 cfm or 3200 cfm.

Available in 4″, 6″, 8″, 10″ and 12″ sizes

Where do I position the inline fan in relation to the filter?

The inline fan can be used as a push or pull system…usually the fan goes after the filter. We recommend you:

1. Make the exhaust run as short as possible
2. Make as few turns as possible
3. Pull in fresh, cool air from the bottom
4. Exhaust hot, used air from top

Air Box premium commercial-grade filters offer the most advanced system for improving indoor air quality

Air Box circulates clean, healthy fresh air.

Replaceable activated carbon filters destroys odors, capture organic and non-organic contaminants and scrub pathogens from the air. Replaceable high-flow carbon filters are made from exclusive 100% premium activated charcoal.

For residential, commercial and industrial environments.

Activated carbon granules are an “absorbent” with well-developed pore structures allowing for a full range of absorbent retention. The high hardness number allows for minimal granular breakage and the kindling point of this activated carbon is usually high. This activated carbon is particularly well suited for removal of airborne particles, neutralize odors, and chemicals, and eliminate germs, viruses, and bacteria. 

To order, go to: http://www.airboxfilter.com