Ceiling Fan Basics 2: Choosing the Right Size Fan

Big ceiling fan for big rooms, medium-size ceiling fan for medium-sized rooms, really big ceiling fan for really big rooms.  Simple, right?  

There’s a lot of information that you can find on the Internet, there’s a lot of information that you can find in catalogs and on fan boxes.  Different stores and different sales staff will probably tell you slightly different things.  So how can you figure out what’s best for your home? 

It takes practice and requires a bit of trust in your friendly, neighborhood ceiling fan salesperson.  Do not base your fan buying decision solely on CFM numbers.  Prioritizing a high CFM over everything else will often lead to a less-than-optimal choice.

  1.  High CFM/airflow is usually good
  2. Comparing CFM numbers within the same brand is usually accurate and will give you a good idea of which fans within the brand are stronger.
  3. Comparing CFM numbers from different brands is unreliable. Despite having a regulated process for measuring ceiling fan airflow, we have seen many instances of cheap, weak fans with small motors claiming to be able to move over 6000 CFM. 
  4. Increasing the diameter of a fan will increase its CFM output, but the added weight of larger blades will cause larger fans to spin slower and generate slower airspeed. This can result in a fan with a very high CFM, but poor “cooling” ability. 

Match the Fan Size to Your Room Size.


In general…

Rooms that are SMALLER than 12 feet x 12 feet will be fine with a fan about 42 inches in diameter.

Rooms that are between 12×12 and 16×16 should get a fan about 50 inches to 56 inches in diameter.  

Rooms larger than 16×16 will probably need a fan that is 60 inches in diameter or larger.

If your room is big enough that it can split up into multiple “zones” of 12×12, it may be a good idea to look at multiple 52 inch diameter fans.

“Obstacles” in the room may limit the size of fan that will fit.  Cabinets, corners/walls that protrude into the room, tall bedposts, bunk beds, and recessed lighting may force you to use a smaller size than these guidelines recommend.  

This sizing typically works well when you purchase a fan from a ceiling fan specialty store, but may not always work with fans purchased at hardware stores.  Cheaper fans are cheaper for a reason.  Hardware stores sell inexpensive fans because they have inexpensive components.  Lower cost = lower price = lower performance.  

The “average” ceiling fan at a ceiling fan specialty store will be more expensive than the average fan from a hardware store, but the performance will be significantly better when you purchase from a specialty store.

Cubic Feet Per Minute

As a general guideline:

4000-5000 CFM at high speed is a good benchmark for small rooms

5000 CFM at high speed is a good benchmark for rooms that are 12×12 or larger

In a living room, family room, or other high-occupancy room, aim for a high speed number that is close to 6000 CFM or higher.

Average or Weighted Airflow Numbers are still new and difficult to compare at this point.

From what we have seen, this is the kind of Weighted Airflow performance that we recommend.

Small rooms (under 12×12): 2500-3000 CFM

Large Rooms (12×12 and larger): 4000 CFM

High-occupancy rooms (family room, living room, etc): 4500 CFM or higher

If you are going to compare CFM numbers, make sure you are comparing fans of the same size.

Whenever possible, feel the fan that you want to purchase.  Regardless of the size or CFM number that is advertised, feeling the fan helps to give you an idea of how each fan will feel in your home.


Other Exceptions

Keep in mind that not all fans are created equal.  The Fan Shop carries 52″ ceiling fans starting below $100 and can range to over $600.  With the more expensive fans, you are often getting better quality, higher airflow, additional features (remote controls, integrated light fixture), and more style.  Some of these things are worth paying more money to get, some are not.  

Where is the room and how do you use it?  If one of your rooms is mostly used in the afternoon and gets the afternoon sun, it would be wise to choose a stronger fan.  If your bedrooms are only occupied at night for sleeping, choose a less expensive fan.  If the bedrooms are used a lot and family members play, craft, read, or lounge in their rooms often, consider a stronger fan for rooms that are used more often.
If you already have or plan to get air conditioning, you can run your fan on medium speed and run your air conditioner at a warmer temperature than usual.  Having the fan circulate cool air from an air conditioner will feel better than just having the air conditioner running and will use less electricity.  


Ceiling Heights and Downrods

Most homes in Hawaii are built with 8-foot ceilings.  Most ceiling fans come with a short downrod to accommodate 8-foot ceilings.  

Hugger or low profile fans keep their blades closer to the ceiling, giving you more headroom.  Moving fan blades just a few inches closer to the ceiling makes it harder for a fan to “breathe” sufficiently.  This results in hugger-style fans generating less airflow than “normal” ceiling fans with downrods.  Whenever possible, The Fan Shop recommends customers to use the short 4″ downrod that comes with their fan and avoid using hugger-style fans, if possible.

For higher ceilings, it may be necessary to purchase a different downrod and install the fan a little closer to the floor.

under 7’8″ – probably best to avoid installing a fan
under 7’8″ to 7’11” – hugger style
8-9: standard downrod (about 4 inches)
10′: 12 inch downrod
11′: 18-24 inch downrod
12′: 36 inch downrod
13′: 48 inch downrod
14′: 60 inch downrod
15′: 72 inch downrod
16′: 72 inch downrod

These heights are also guidelines.  if you have tall family members or your design sense tells you that a shorter downrod is better, than feel free to go with a shorter downrod and raise the fan a bit.  We would discourage you from using downrods longer than the recommended sizes, doing so may result in the fan blades hanging at an unsafe level.  


When to Choose an Outdoor Fan

There are 2 types of outdoor fans: Damp Rated fans and Wet Rated fans.

Damp Rated fans can be installed in covered patios and should not be directly exposed to rain.  
Wet Rated fans can be installed outdoors.  They can be rained on and will still be electrically sound.  
Both types fan can also be installed indoors, but Indoor Rated fans should not be installed outdoors.  Damp-Rated and Wet-Rated fans almost always come with plastic blades for longer lasting durability.  

For homes that are near the ocean, outdoor fans are a wise investment, even for inside your home.  The plastic blades will last much longer than even high-quality plywood blades.  

Keep in mind that Damp Ratings and Wet Ratings are electrical ratings, not corrosion resistance ratings.  Most outdoor fans still have a lot of metal in them and home owners that live near the ocean should take some time every 2-3 months to dust or wipe down their fans.  Taking the time to clean your fans 2-3 times per year can help the finish of your fan last for many, many years. 

We hope that helps and hope to see you again soon.