What is the best ceiling fan size?
We can agree that you can’t pick just any ceiling fan size. You need to size a fan to how big a room you want to put it in. A properly-sized ceiling fan can provide ventilation and improve comfort year-round.
We are going to look at all ceiling fan sizes and use a ceiling fan size guide (found below) to adequately pick the size of ceiling fan you need. A vital part of this process is also how to measure a ceiling fan size (you will find a spet-by-step way for both odd-number and even-number of blades; you have to determine the diameter of the blades).
Here’s the deal:
A lot of homeowners get the size of the ceiling fan wrong. They buy a ceiling fan that’s either too big or too small. How to determine ceiling fan size? Navigating ceiling fan blade diameters, CFMs, and room square footage is, as you might imagine, not all that easy; hence the sizing mistakes are made.
Example: What should a ceiling fan size be for a 12×12 room? A 48-inch fan is too big. A 36-inch fan is too small. A 42-inch ceiling fan is just right for a 12×12 room.
As you can see, the size of ceiling fans is measured in the diameter of the blades. We talk about 36-inch, 42-inch, 48-inch, 52-inch, 60-inch ceiling fans, and so on. In HVAC, however, we primarily focus on airflow generated (measured in CFMs or Cubic Feet per Minute).
The diameter of blades (ceiling fan size) is proportional to the CFMs a ceiling fan can generate. Adequate ceiling fan sizing simply means that you figure out how many CFM ceiling fans you need. An easier way (albeit less accurate) to size a ceiling fan is just to check the ceiling fan blade diameter and room square footage.
The ceiling fan size guide below includes both the room sizes (in square feet and width×length), ceiling fan blade size appropriate for such rooms, as well as estimated CFM airflow output.
Note: This size guide is valid for standard 8 ft ceiling height. Below the chart, we illustrate how to size a ceiling fan for higher-than-8-ft ceiling height. We also explain how to measure ceiling fan size for an odd number of blades (3-blade, 5-blade fan) and even the number of blades (4-blade, 6 blade fans).
On top of that, we also look at 2 real-life examples (average bedroom and 10×10 room) of how to measure the ceiling fan size and estimate how many square feet room such a fan can adequately cover:
Ceiling Fan Size Guide
| Room Size: | Dimensions: | Blade Size: | Adequate CFM: | Room Example: |
| Less than 50 sq ft | 6×6, 6×8 rooms | 29 inches or less | 1000-2500 CFM | Small Bathroom |
| 50 to 75 sq ft | 8×8, 10×6 rooms | 29 to 36 inches | 1200-2800 CFM | Small Room |
| 75 to 100 sq ft | 8×10, 10×10 rooms | 36 to 38 inches | 1500-3500 CFM | Standard Bathroom |
| 100 to 150 sq ft | 10×12, 12×12 rooms | 38 to 42 inches | 2000-4000 CFM | Standard Room |
| 150 to 200 sq ft | 12×14, 14×14 rooms | 42 to 46 inches | 2500-4500 CFM | Big Bathroom |
| 200 to 300 sq ft | 15×15, 16×16 rooms | 46 to 52 inches | 3000-5000 CFM | Big Room |
| 300 to 400 sq ft | 18×18, 20×20 rooms | 52 to 54 inches | 4000-6000 CFM | Small Apartment |
| 400 to 500 sq ft | 20×22, 22×22 rooms | 54 to 56 inches | 5000-7000 CFM | 2 Rooms |
| 500 to 750 sq ft | 24×24, 25×25, 26×26 rooms | 56 to 70 inches | 6500-9000 CFM | 3 Rooms |
| 750 to 1,000 sq ft | 28×28, 30×30 rooms | 70 to 84 inches | 8500-12000 CFM | 4 Rooms |
| 1,000 sq ft or more | 32×32, 34×34 rooms | 84 inches or more | 10,000+ CFM | 4+ Rooms |
This ceiling fan size chart is pretty self-explanatory. Bigger rooms will require ceiling fans with longer blades that can generate higher airflows.
Example: Let’s say you have a 14×14 bedroom and would like to know what size ceiling fan you need for such a bedroom. Check the ceiling fan size chart above, look at 150-200 sq ft size (14×14 is 196 sq ft), and you can see you will probably need a 46-inch ceiling fan with about 4000 CFM airflow.
Now, if you already have a fan or you’re buying a fan for a certain room, you will have to know to measure ceiling fan size.
Let’s look at how we can measure fan blade size:
How To Measure Ceiling Fan Size? (Diameter Of Blades)
We talk about 36-inch, 42-inch, 52-inch ceiling fans, and so on. In short, that is the size of a ceiling fan. When sizing a ceiling fan it’s quite useful to know how to measure the ceiling fan size.
Note: Do you know the different directions of blades spinning in the winter vs summer? You can check the correct clockwise vs counterclockwise direction for both seasons here.
Namely, we are measuring the span of the blades. There are two ways how to measure the size of a ceiling fan, depending on a fan having an even number of blades or having an odd number of blades:
- Even number of blades ceiling fans. These are 4-blade or 6-blade fans.
- Odd number of blades ceiling fans. These are 3-blade or 5-blade fans.
It’s easier to measure the length across the blades with even number of blades fans. Let’s start with even ones, and we’ll show how to do it for odd ones after that.
Here’s how to measure ceiling fan size for even number of blades:
- Stop the fan before measuring.
- Use a ladder to reach the ceiling fan, or dismantle it for easier measurement.
- Use a measuring tape. With even blade fans, stretch the measuring tape from the tip of one blade to the tip of the blade opposite the first blade.
- Label the measured ceiling size.
- Stop the fan before measuring.
- Use a ladder to reach the ceiling fan, or dismantle it for easier measurement.
- Use a measuring tape. With odd blade fans, stretch the measuring tape from the tip of one blade to the center of the ceiling fan. You’re measuring the radius of a fan.
- Use the measured radius of the fan and multiply it by 2. The result is the diameter of the fan blades; the ceiling fan size.
- Label the measured ceiling size.
Here’s an example for an odd number fan: Let’s say you have a 3-blade fan and would like to measure the fan size. As per the 3rd step, you measure from the tip of a blade to the center and get the result: 21 inches. This is the radius. Here is how to get the full size of an odd-number blade ceiling fan:
Size Of Ceiling Fan = 21 Inches × 2 = 42-Inch Fan
If you consult the ceiling fan sizing chart above, you can see that a 42-inch fan is appropriately sized to provide ventilation to 150-200 sq ft rooms.
You will have to augment the ceiling sizes a bit if you have a high ceiling. Let’s look at how to size a ceiling fan for high ceiling rooms:
High Ceiling Rooms (You Will Need A Bigger Ceiling Fan)
Any ceiling fan should provide adequate ventilation in a room. We primarily base the size of the ceiling fan on square footage. What we shouldn’t omit, however, is to account for rooms that have a higher than standard 8 feet ceiling height.
A ceiling fan ventilates the air in the room. Higher ceilings equal more air, and therefore you will need a bigger ceiling fan in high ceiling rooms. This is to maintain the recommended ACH (Air Changes per Hour) airflow.
Every foot of height above 8 ft will increase the ceiling fan CFM requirement by 12.5%. Here’s how much more airflow will high ceiling rooms require:
- Standard 8 ft ceiling height. Example: 2,000 CFM.
- 9 ft ceiling height needs 12.5% more airflow. Example: 2,250 CFM.
- 10 ft ceiling height needs 25% more airflow. Example: 2,500 CFM.
- 11 ft ceiling height needs 37.5% more airflow. Example: 2,750 CFM.
- 12 ft ceiling height needs 50% more airflow. Example: 3,000 CFM.
- 13 ft ceiling height needs 62.5% more airflow. Example: 3,250 CFM.
- 14 ft ceiling height needs 75% more airflow. Example: 3,500 CFM.
CFMs are easier to calculate than the actual ceiling fan blade span. To get determine the size of the ceiling fan correctly, you can check the CFM airflow output in the chart above.
In practice, this would mean that for a 12×12 room with a 14 ft ceiling, the 42-inch fan won’t be enough. You should opt for a 46-inch or even 48-inch ceiling fan to account for the additional air in the room due to the higher ceiling.
Let’s solve two examples of how to correctly size a ceiling fan:
Ceiling Fan Size For Bedroom (Example 1)
An average bedroom size in the US is 14×16 feet or 224 square feet. How what size ceiling fan do you need for such a bedroom?
If you have an 8 ft ceiling height, you can simply check the ceiling fan size guide for bedroom sizing above. You can see that for 200-300 sq ft bedrooms, you require 46-52 inch bedroom fans (generating 3000-5000 CFM airflow)
Since 224 sq ft is closer to the 200 sq ft mark, you will most likely need a 48-inch ceiling fan for an average bathroom. Such a fan will generate about 3500 CFM airflow and will adequately ventilate your bedroom.
If you have a higher than 8 ft ceiling, you will need a bigger ceiling fan for the bedroom. You add 12.5% for every extra foot of height, and your options will be in the range between 52-56 inch bedroom ceiling fans.
Ceiling Fan Size For 10×10 Room (Example 2)
10×10 is one of the most common room sizes. This is basically a 100 sq ft room. What size ceiling fan do you need for a 10×10 room?
You simply check the chart above. 75-100 square feet rooms need 36-inch or 38-inch ceiling fans. Since 100 sq ft is exactly the upper range here, you would obviously need a 38-inch ceiling fan for a 10×10 room.
That’s if you have a standard 8 ft ceiling height. With higher ceilings, you’re looking at 42-46 inch fans; those higher flow ceiling fans will be enough to ventilate 10×10 rooms with higher ceilings.
Hopefully, this illustrates how you go above picking the ceiling fan size.
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