How To Measure A Ceiling Fan | Ceiling Fan Size Guide

Measuring a ceiling fan

Sizing 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.

There’s a few things you have to ask yourself first:

  • 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.

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How To Measure A Ceiling Fan

First up … 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:

  1. 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.
  2. 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.

Next … 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.

  • Recommended blade size diagramLess 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. Find out what a flush mount ceiling fan is.

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

We’ve got you covered for guides on how to install ceiling fans:
How to install a ceiling fan without attic access
How to install a ceiling fan where no fixture exists
How to hang a ceiling fan without a stud
Installing a ceiling fan where a light fixture exists

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.

Other Considerations

There are a few other things you need to think about when considering what ceiling fan size you need to for your room, as no ones situation is the same, every room is going to be slightly different from one another.

  • How strong is your ceiling?
    When considering a ceiling fan, you first need to ensure the strength your ceiling is up for the job! Whether you are going to purchase a small lightweight fan or a large industrial size fan with lights, you need to make sure your ceiling can support it.
    Generally, when purchasing a ceiling fan the manual will specify what supports you need, however if you are in any doubt, it’s best to get the opinion of a professional, so ask a contractor to pop around to assess your ceiling.
  • Will anything obstruct the fan?
    This may be obvious, but some people overlook this crucial part. Are there any obstacles in the vicinity of where you want to place your fan? Sloped ceilings, light fixtures or decorations – the list could go on. Make sure you think about this when purchasing your ceiling fan along with picking your downrod length.
  • Do you want a ceiling fan with lights?
    This one is quite easy to overlook. If you are planning on purchasing a ceiling fan with lights, or purchasing a ceiling fan light kit to add to an existing fan, remember that this will add depth to your fan measurement. Depending on what style fan and lights you go for, the measurements can change dramatically, so just make sure you remember!


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.