This fan CFM calculator is typically used to calculate the cubic feet per minute of air exchange that may be desired in a building. Whether exhausting air or bringing fresh air into a structure, the calculation produced should help to figure out the size of fan(s) required to accomplish the air exchanges needed.
If you are not sure what kind of CFM's may be needed for your type of facility, please refer to the Commercial & Industrial Applications chart below.
*PLEASE NOTE: this calculator is not intended to be used to calculate for air circulation or HVLS fans. If you have any questions regarding CFM's, air exchanges needed, the calculator, or which exhaust and or supply fans may be right for your building, please call us at 866.727.1060
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View products that meet your CFM requirements:
Standard
Explosion Proof
Roof Exhaust Fans
Wall Exhaust Fans
Roof Intake Fans
Wall Intake Fans
Duct Inline Fans
CFM = Room Volume / Minutes Per Air Exchange | Room Volume =
Minute Air Exchange Chart For Commercial and Industrial Applications
Typical | Range | |
|---|---|---|
| Assembly | 6 | 2-10 |
| Auditoriums | 6 | 1-20 |
| Bakeries | 2 | 1-3 |
| Banks | 6 | 3-10 |
| Bars | 4 | 2-5 |
| Barns | 15 | 10-20 |
| Boiler Rooms | 2 | 1-3 |
| Bowling Alley | 3 | 1-5 |
| Cafeteria | 4 | 3-5 |
| Churches | 6 | 2-10 |
| Classrooms | 6 | 4-8 |
| Compressor Rooms | 2 | 1-3 |
| Dance Halls | 6 | 2-10 |
| Dairies | 4 | 2-5 |
| Dormitories | 6 | 4-8 |
| Dry Cleaning Plant | 3 | 1-5 |
Typical | Range | |
|---|---|---|
Engine Rooms | 3 | 1-5 |
Factories | 7 | 4-10 |
Foundries | 5 | 2-8 |
Garages | 7 | 4-10 |
Generating Plants | 4 | 2-5 |
Glass Plants | 2 | 1-3 |
Gymnasiums | 6 | 2-10 |
Hallways | 8 | 4-12 |
Kitchens (Comm.) | 3 | 1-5 |
Laboratories | 3 | 1-5 |
Libraries | 4 | 2-5 |
Laundries | 2 | 1-3 |
Locker Rooms | 6 | 2-10 |
Machine Shops | 4 | 2-5 |
Markets | 6 | 2-10 |
Mills | 4 | 2-5 |
Typical | Range | |
|---|---|---|
| Packing Houses | 4 | 3-5 |
| Plants | 7 | 4-10 |
| Plating Plants | 4 | 2-5 |
| Print Shops | 7 | 4-10 |
| Restaurants | 6 | 2-10 |
| Rest Rooms | 7 | 4-10 |
| Schools | 7 | 4-10 |
| Spray/Paint booth | 1 | 1-2 |
| Stores | 7 | 4-10 |
| Theaters | 6 | 4-8 |
| Transformer Rooms | 3 | 1-5 |
| Turbine Rooms | 4 | 2-5 |
| Waiting Rooms | 12 | 10-15 |
| Warehouses | 7 | 4-10 |
| Welding Rooms | 3 | 1-4 |
CFM Calculation
Calculating CFM’s is a skill that any contractor who's worth their salt can perform. This technique measures airflow in a room to determine several factors like proper fan sizing and air exchange rates according to safety and construction standards. Different rooms such as bakeries, bowling alleys, and welding rooms require different air changes and air flow for their specific functions. Homeowners can also learn how to calculate CFM’s and ensure high indoor air quality with these simple guidelines.
1. Use a cubic feet per minute calculator device
While this advice may appear counterproductive, it will help you get a 'better feel' for the ideal air velocity in hands-on situations. It's a good idea to use a device that's easy to operate and is Bluetooth compatible so you can record the data for future study.
2. Know how to measure in more ways than one
Basing your fan calculation from an air balancing hood alone seems like a good idea but is actually off 10% of the air duct system's designed capacity. Most small fans can be installed with this variation, but more accurate measurements are required for larger fans. To overcome this, learn how to measure the CFM via at least two different fan calculator methods. The Plot Plan Airflow and Airflow Traverse strategies are good examples.
3. Learn basic fan calculation formulas
This practical math formula goes a long way when you're considering air ventilation improvement in an indoor space:
CFM = (fpm * area)
CFM (Cubic Feet per Minute) is calculated by multiplying the velocity (Feet per Minute) with the area (Square Feet).
Example CFM calculation:
Question: I have a warehouse that I want to exhaust hot, stale air from and replace with fresh air. How much CFM will I need?
Answer: The first step is to measure the dimensions of your space, including the height of your ceilings. Once you have those numbers, you want to decide how many air exchanges work for that setting. For example, warehouses typically require 7 air exchanges an hour to notice a difference in air quality. With your space being 25’ L x 50’ W x 75’ H, we would recommend somewhere between 14,000 to 15,000 CFM.
FAQs
How do you calculate CFM?
To calculate CFM (Cubic Feet per Minute):
1. Measure airflow in a specific area (e.g., duct)
2. CFM = (Velocity in feet/minute) × (Area in square feet)
How much CFM do you need per square foot?
For general HVAC purposes, the typical recommendation is approximately 1 CFM per square foot of floor area. However, this can vary depending on your specific needs, like room occupancy or the presence of certain appliances. Contact the Industrial Fans Direct team if you need help determining your requirements.
Can CFM be too high for a room?
Yes, CFM can be too high for a room. Excessive CFM can cause draftiness, increased energy costs, and ineffective humidity control. It's essential to match the CFM to a room's size and purpose to ensure comfort and optimal system efficiency.
