Short answer: CFM is an acronym that stands for cubic feet per minute, and is a measure describing airflow volume.
When looking into systems such as air con, or fans of any description, you will usually come across the term “CFM”, with manufacturers trying to entice you to buy their products by stating how high each product’s CFM value is.
But if you’re not familiar with the term, it means nothing to you. This is why I decided to put this article together for you, so that you understand exactly what it means, and then use that information to help you decide what ceiling fan CFM best suits your needs.
In this article, I’ll kick things off with the basics, describing how CFM is measured, and why it’s important, and following that up with the factors that can affect a ceiling fan’s CFM, and then going on to describe what ceiling fan CFM you will need for different room sizes and wrapping up with a brief conclusion.
And without further ado, let’s get straight to it!
How CFM is measured?
First off, don’t worry. Unless you’re working for a fan manufacturer, you’ll never be asked to work out the CFM of a fan.
However, for the sake of completeness, we’ll go over it briefly. Basically, in an enclosed space, a stationary point is identified, and a static pressure probe is used to measure how many cubic feet of air passes by it in the space of one minute.
What is a good CFM airflow?
The higher the CFM of a fan (including but not limited to ceiling fans) the higher the volume of air pushed through by the fan.
And what this means is that smaller rooms, such as small bathrooms or walk-in closets, won’t need a fan with a high CFM, because there’s less air required to flow around the room in order to achieve the same level of incoming cool air.
Likewise, for a large room, such as a large living room or reception room, a greater airflow is required in order to achieve the same effect, if you wish to experience the same level of incoming cool air throughout the room.
Therefore, what might be a good CFM value for airflow in one room, may not necessarily be suitable for another, bigger room.
You don’t have to do any fancy calculations to work out the best CFM for each of your rooms, however, later on in this article, I will go through the best CFM values to look for in a ceiling fan for rooms of different sizes.
But for now, let’s take a look at the different factors that can affect a ceiling fan’s CFM.
Why getting the right CFM is important?
So, now that you know a higher CFM means a greater volume of airflow every minute, you may be tempted to believe that it’s always a case of going for as high a CFM as possible in all of your ceiling fans. But, actually, that’s not always the better option. Let me explain…
If the CFM of your ceiling fan is too high, this can cause ventilation issues. Too much airflow in too little ventilation can lead to high humidity levels. And this excess of moisture can lead to issues such as mold and mildew, which in turn can be detrimental to your health.
Factors that can affect a ceiling fan’s CFM
There are three main factors that can affect a ceiling fan’s CFM and airflow. Allow me to walk you through…
RPM is an acronym that stands for rotations per minute, and it describes the speed of the ceiling fan, specifically how many times it rotates 360 degrees in the space of one minute.
The higher the RPM, the greater the speed of the fan, and the greater the amount of airflow that can pass by a stationary point in the room per minute.
Ceiling fan size and its blades are a great factors to consider. The bigger the blades of your ceiling fan, the more air can be pushed through per minute, resulting in a greater CFM.
Standard ceiling fans typically have a blade size ranging between 40 and 65 inches, but you may be able to buy smaller or larger ones online.
In order to be able to push air around a room, the blades of ceiling fans are typically set at an angle. The greater this angle, the more air can be moved per rotation, resulting in a greater CFM. Most ceiling fans have blade angles of at least 13 degrees.
The smoother the blades are, and more aerodynamic, the less air friction there is to disrupt the airflow, resulting in a greater CFM.
What ceiling fan CFM you will need for different room sizes?
As mentioned earlier, the higher the CFM of a fan, the higher the volume of air pushed through by the fan. Therefore, larger rooms will require a higher CFM than smaller rooms.
And as promised, here follows an easy-to-follow chart laying out the recommended CFMs for rooms of various sizes.
|Typical Room||Room Size||Recommended CFM|
|Small Room Or Closet||Under 200||2,000 to 3,000|
|Standard Bedroom||200 to 300||3,000 to 4,000|
|Master Bedroom||300 to 450||4,000 to 6,000|
|Large Living Room||Over 450||5,000 to 9,000|
So, in summary, CFM stands for cubic feet per minute and is a way to describe the rate at which a volume of one cubic feet worth of air can flow by a stationary point per minute.
The larger the room, the higher the CFM that’s required. It’s important to get this right, because you want the fan to be effective in circulating air flow, but you don’t want the humidity to be too high.
Factors that can affect the CFM of a ceiling fan include the speed of the blades, the size of the blades, the smoothness of the blades, and the angle at which the blades are set.