How Are Ceiling Fans Measured?

How are ceiling fans measuredSizing ceiling fans might seem like a no brainer.

You measure the room, run some numbers, ask your interior designer and decide what size to buy, right?


The measurement of the room alone rarely suffices in helping pick the right sized ceiling fan.

There’s a lot more to it.

So, to the question in hand – how are ceiling fans measured?

  • Do you have an island false ceiling?
  • How do you plan to hang the fan?
  • What type of windows do you have (sliding, opening inwards, outwards)?
  • How tall are the cupboards?
  • How are the lighting fixtures positioned?
  • More importantly, will the ceiling fan be too big for the room?

That’s a common but rookie mistake. Buying an oversized fan in a small room overwhelms it making it appear smaller than it is.

Contrarily, buying a small sized fan in a large room reduces the efficiency of the fan and burns out the motor faster.

How then, does one pick the right sized fan for their homes?

Before we get into the details, let’s take a look at how ceiling fan sizes are determined.

The Sweep / Blade Span

When you go ceiling fan shopping, you will notice that the size of the fan is measured in inches. 36, 48 and so on! This is called the sweep or the blade span of the fan.

There are two ways to determine this number and it depends on the number of blades on the fan:

  • If the ceiling fan has an odd number of blades (3,5), measure the distance from the center of the fan to the tip of any of the blades. Multiply this number by 2 and you have your blade span or fan size.
  • If the ceiling fan has an even number of blades (2,4), measure the distance from the tip of one blade to the tip of the blade on the opposite side to find the blade span.

The Measurement of Your Room

Determine the square footage of the room by multiplying the length and the width.

Now, here’s a ballpark table that shows the square footage of a room with the corresponding recommended fan size.

  • What Size Ceiling Fan Do I Need?Less than 75 sq. ft. (Bathrooms, utility rooms or porches) = 29 to 36 inches
  • 75 to 144 sq. ft. (Small bedrooms, utility rooms) = 36 to 44 inches
  • 144 to 225 sq. ft. (Dining rooms, porches, small sized kitchens) = 44 to 54 inches
  • 225 to 400 sq. ft. (Master bedroom, a small garage or an entertainment room) = 50 to 72 inches
  • Anything more than 400 sq. ft. (Large sized rooms, living rooms, basements) = Multiple fan installations of 50-72 inches

Please remember that this is just an estimated number. The other factors that we mentioned would still have to be taken into account.

How Many Ceiling Fans Per Room?

As mentioned above, if you have a large room that is more than 400 square ft you should consider multiple fan installations to help evenly distribute the airflow throughout the room.

Hanging The Fan

Depending on the type of ceiling in the room, you’d have to decide how high to hang the fan and choosing the right sized downrod.

A ceiling hugger or a flush design that sticks close to the ceiling without a downrod is preferred for ceilings that are lower than 10 feet in height.

For ceilings above 10 feet, you’d typically need a downrod. The length of the downrod can vary depending on the room size.

How are ceiling fans measured - downrod diagram


The air circulation capacity of a ceiling fan is measured in Cubic Feet Per Minute or CFM and this number can vary from 50 to 110. The larger the fan size the higher the CFM. But the caveat is that a higher CFM rating usually means that the fan guzzles power.

Ideally, you should look for a CFM rating that corresponds with low power usage to ensure that you have an energy efficient ceiling fan that can help reduce power bills in summer and keep the thermostat low during winters.


As you can see, there’s a lot more to consider when purchasing a ceiling fan then simply whether it looks good, has LED light bulbs or wireless capabilities (obviously those are important too!). It really pays to do your research and calculate what size fan you are going to need for your room.

Hopefully this article has assisted you in choosing the perfect size fan for your home. Take a look at our article on the best ceiling fan brands to help you decide which brand is right for you.