Fan CFM Calculator
This fan CFM calculator will help you pick a great fan for your space or application. Whether it's a bathroom fan, an industrial application or any sort of exhaust fan, this calculator will help you get the right cfm and help you with sizing industrial exhaust fans. You can also use this for figuring out how to calculate cfm for hvac applications. This calculator was built specifically as an exhaust fan cfm calculator. As you change the room height, ACH, type of room and the area, the cfm calculator tool will automatically show you the right fans that you can choose from.
Unit to use
Area of space (sq ft)
Ceiling height (ft)
A guideline CFM calculation for a bedroom:
If you know the ACH you need, you can use the cfm calulator below instead.
What is CFM?
CFM stands for Cubic Feet per Minute. It's a measure of the flow of airThe higher the CFM number, the more air is pushed by exhaust fan, air conditioner, air purifier, heater, or any other HVAC device.
Another important factor to consider when deciding to buy a fan or HVAC item is to consider the ACH, or Air Changes per Hour for a room, or your application. The ACH is just that, how many times per hour that all the air is changed or replaced in the spaceGenerally, public places and places with poorer air quality need a higher ACH value to preserve air quality.
What CFM do I need?
So, how much cfm do I need? Generally, the bigger CFM the better. Some exhaust fans here also include different speed motors, so you can be flexible about choosing that particular model. There are different methods to calculate what different exhaust cfm you need. As a general rule of thumb, you’ll need about 0.1 to 1 CFM per square foot of space for your application. The lower end (0.1 CFM per sqft) is for cleaner, less moist environments. The higher end (1 CFM per sqft) would apply to stuffy, hot and moist or dirty areas like garages, offices and warehouses. If in doubt, pick a higher CFM. You can always buy multiple fans of lower CFM to account for a larger demand. For example, 2 fans with 500 CFM for a 1000 CFM suited area.
How many cfm per square foot?
Generally, you want 1 cfm per square foot. You can use the calculator above to factor in the height of the room too.
How to calculate cfm for different areas?
Of course, different spaces need different types of fans, some might need more throughput, while others not so much. Below is a table that show a guideline to calculating the cfm for the space. It provides the rough ACH for the type of area. This is used in the above fan cfm calculator, which you can use.
|How many CFM for a basement?||3-4|
|How many CFM for a bedroom?||5-6|
|How many CFM for a bathroom?||6-8|
|How many CFM for a living room?||6-8|
|How many CFM for a kitchen?||7-8|
|How many CFM for a laundry?||8-9|
|How many CFM for a business office?||6-10|
|How many CFM for a lunch break room?||7-8|
|How many CFM for a conference room?||8-12|
|How many CFM for a medical procedure office?||9-10|
|How many CFM for a copy room?||10-12|
|How many CFM for a main computer room?||10-14|
|How many CFM for a smoking area?||13-15|
|How many CFM for a dining area?||8-10|
|How many CFM for a food staging?||10-12|
|How many CFM for a kitchens?||14-18|
|How many CFM for a bar?||15-20|
|How many CFM for a hallway?||6-8|
|How many CFM for a retail store?||6-10|
|How many CFM for a foyers?||8-10|
|How many CFM for a restroom?||10-12|
|How many CFM for a church?||4-12|
|How many CFM for a gym?||6-30|
|How many CFM for a factory?||12-30|
|How many CFM for a laboratory?||12-60|
|How many CFM for a laundry (public)?||20-60|
|How many CFM for a toilet?||12-30|
|How many CFM for a warehouse?||6-30|
How much CFM for a room?
So how to calculate cfm for a room? The below table gives some sample values for a CFM at different room sizes. This assumes an 8ft ceiling height and 5 air changes per hour.
|How many CFM for a 100 sq ft room?||67|
|How many CFM for a 200 sq ft room?||133|
|How many CFM for a 300 sq ft room?||200|
|How many CFM for a 400 sq ft room?||267|
|How many CFM for a 500 sq ft room?||333|
|How many CFM for a 600 sq ft room?||400|
|How many CFM for a 700 sq ft room?||467|
|How many CFM for a 800 sq ft room?||533|
|How many CFM for a 900 sq ft room?||600|
|How many CFM for a 1000 sq ft room?||667|
|How many CFM for a 1500 sq ft room?||1000|
|How many CFM for a 2000 sq ft room?||1333|
|How many CFM for a 2500 sq ft room?||1667|
The CFM calculation formula is made up of the room area, room height and air changes per minute.
How to calculate the CFM for a room?
For a bedroom or any residential room, an ACH of 5 is roughly the value to use. Let's say the room is 1000sqft and 8ft tall:
So the ideal CFM for a fan for this room would be around 667 CFM.
How to calculate cfm of a fan?
CFM is just the amount of air per minute moved.
If you know the diameter of the fan, and the average pitch or depth of the blades, you can calculate the CFM of the fan yourself. If you think of a fan spinning, it forms a cylinder shape that is the whole volume of the fan. If you calculate the times it "fills the cylinder" up every minute, that's the CFM of the fan!. This can be roughly expressed as the cfm formula:
- When the RPM increases, CFM goes up.
- When diameter increases, CFM goes up (a lot).
- When number of blades increases, CFM goes up.
- When depth of the blades goes up, CFM goes up.
Where r = the radius of the fan, b = the number of blades, h is the average height of a blade, and rpm is the revolutions per minute of the fan. All measurements in feet, for the formula above.
Use the calulator below to calculate the cfm of a fan:
No. of blades
Height of the blades (in.)
Diameter of the fan (in.)