Outdoor Fan Blades


How Does an Outdoor Fan’s Blades Affect Your Choice of Fan?

Not only the blades’ size but also their number, shape, speed of rotation, angle, and even the material they’re made of can affect the cooling ability of an outdoor fan. A smart choice of fan blades can maximize the fan’s air flow and cooling ability.

blades are an important element of a ceiling fan’s style. Knowing how the blades work can help you choose a fan that is stylish and effective – especially good to know if you can customize the blades.

Will that big, powerful-looking floor fan really cool your workshop in August, or does it just look like it will? Knowing a little about the fan blades can help you make a smart purchase.

Blades Determine the Size of Outdoor Fans

The size of an outdoor fan is based on the size of the fan blades – straight across from blade tip to blade tip. The longer and the wider the fan blades the more air they will move. The size of the area you need to cool will help determine the size of the fan to use.

The following outdoor ceiling fan size chart shows some typical outdoor fan sizes and their recommended areas for cooling. Fan size is based on the measurement of the outdoor ceiling fan blades.

This chart is just to give you a general idea – the numbers are extremely flexible depending on the configurations of any one fan (its CFM / CMM, efficiency, and wattage) and of any one area. Large areas may require more than one fan. Rectangular, odd-shaped areas or partially divided areas are best cooled by multiple smaller fans that can direct airflow into hard-to-reach places.

32″ / 81 cmup to 64 / up to 6up to 8×8 / up to 2.4×2.4Small porch, shed, baseball dugout
34-36″ /86-91 cmup to 100 / up to 9.310×10 / 3×3Gazebo, greenhouse, festival booth
38-42″ / 96-106 cmup to 144 / up to 13.412×12 / 3.7×3.7medium patio, carport
44-46″ / 112-117 cmup to 225 / up to 20.915×15 / 4.6×4.6large patio
48-54″ / 122-137 cmup to 400 / up to 37.220×20 / 6×6medium courtyard
56″ / 142 cmup to 485 / up to 4522×22 / 6.7×6.7barn, pavilion
58-60 / 147-152 cmup to 600 / up to 55.725×25 / 7.6×7.6event tent, livestock shelter
General fan sizes and areas they can cool. These numbers are for general reference only and do not apply to any particular style of mount or installation.

This chart is for general reference and does not apply to any particular style of mount or installation. For example, most standing fan’s blades are simply not that large. Plus standing fans of comparable sizes generally move more air than ceiling fans.

The amount of CFM or CMM needed to cool an area is about 3 to 4 times the area.

You can use a conversion calculator to easily switch between measurements.

Larger Outdoor Fans Aren’t Always Better

It’s often better to use several smaller outdoor fans than one large fan. More, smaller fans can ensure air movement in more areas than just one fan can. You’ll also be able to use lower fan speeds to get good airflow — softer breezes can be less of a nuisance than stronger breezes. Smaller fans also allow you to concentrate the air flow exactly where you need it. Why fan a whole patio if you only use a corner of it?

Keep at least 24″ / 60 cm between the blades of multiple fans. This ensures the airflow of one fan doesn’t cancel out the airflow of another.

porch with two small ceiling fans

Consider using a combination of outdoor fan styles. A small ceiling fan can be used to cool the middle or one side of a patio and a standing fan or table fan can reach the corners.

An open area will allow that moving air to cover as large an area as possible, but will also allow it to dissipate. For example, a canopy or gazebo that’s open on all sizes will likely need a larger fan than the same sized area closed on two or more sides. A good general rule to determine how many outdoor fans to use in an open area is that you want to create some air movement where most people will be most of the time.

Since there are no walls or ceilings in completely open areas, you will need to use a free-standing fan such as a pedestal or standing fan, a floor fan, or even a table fan sitting on a wall or ledge.

Especially with floor fans, the air flow originates low to the ground, meaning people moving in front of it can more easily block the airflow. You can lower the chances of that if you use an oscillating fan, or several fans set up around the area to “bathe” it with moving air.

How Many Blades Should An Outdoor Fan Have?

Is a 4- or 5-blade ceiling fan better?

Three is generally the most efficient number of fan blades for outdoor cooling. Four to six blades are usually used because the extra 1 to 3 blades make for a quieter fan. More blades than six is almost always less efficient, but it can be more decorative – especially important for ceiling fans. Fewer than three blades don’t take advantage of a motor’s power and move less air. Choose a three-blade outdoor fan when noise level is not as important but cost and efficiency are crucial.

Any more than six fan blades can put more strain on the motor than the resulting air movement would justify. The exceptions are specialty outdoor ceiling fans that may use up to ten blades and extend 24 feet across. These use a combination of specialized outdoor ceiling fan blades and motors.

The Shape of the Fan Blades

The wider the blade, the more air it will move … up to a point. The fan blades on some very decorative fans can be so wide they would nearly overlap each other. This may not allow enough air in between the blades for good air movement. If beauty is more important than maximum airflow, these can be a fine option.

Some fans have just the tips of their blades tilted. This doesn’t “even out” the air flow the way tilting the entire blade does, but it can enlarge the area a fan affects. This is often seen in standing fans.

Still, other fan blades have specialized shapes. Some are shaped like airplane wings with more surface area on the top than on the bottom. Some curve forward. You may need to contact the manufacturer to learn how these special shapes affect the air flow.

Outdoor Fan Speed / Fan Blade Rotation

Faster blade rotation is basic to greater airflow, which means greater cooling. Blade rotation is sometimes called “fan speed” and is measured in RPM (revolutions Per Minute). It is simply the number of times any one blade makes a full rotation in one minute. An outdoor fan with two speeds will have a lower RPM with less air flow on LOW and a higher RPM with greater airflow on HIGH. Look at the CFM / CMM rating for each speed.

Blade Pitch and Tilt

The angle at which the fan’s blades are angled up from the flat plane of their rotation is referred to as the “blade pitch”. The greater the pitch, the greater the airflow. But as pitch increases so does the drag. So as the pitch increases, so must the power of the motor. Blade pitch usually varies between 9 and 15 degrees. Very strong motors can drive blades with a pitch in the 20s which makes for exceptional air flow.

Some outdoor fans modify not only the pitch of the blades but also their tilt. Tilting the fan blades back (or up, in the case of ceiling fans) distributes the blowing air more evenly around an area. So there’s less airflow directly in front of the fan, but more in the outer reaches of the fan’s airflow. The airflow is “evened out.”

Blade Materials

Fan blades should be made of sturdy, warp-resistant materials. An outdoor fan, being exposed to much harsher elements than an indoor fan, needs to have blades that resist corrosion and warping. The most common materials are aluminum and various kinds of plastics, such as ABS. Heavy-duty fans may also incorporate fiberglass into their plastic / polypropylene blades.

Materials like rattan and most woods won’t hold up to long periods of outdoor use. But aluminum and plastics can be treated to look very much like them and still be durable enough for outdoor use.

A common cause of drooping fan blades is simply attachment screws that loosen over time. This can be fixed by tightening the screws with an ordinary screw driver. But when the material, itself droops or warps, the fan blades may need to be replaced. Look for lightweight, durable blades that are the same size as the original blades.

What Makes a Great Outdoor Fan?

Learn all about Outdoor Fans in our other In-Depth articles on what to look for in a great fan:
1. the fan, itself: The motor, energy use and air flow determine how much cooling you can expect from a fan. The fan blades (this page) determine the size of the fan and can really maximize that air flow.
2. A fan’s features are especially important for outdoor fans since they must be safer and more durable than indoor fans. Look for features such as:

  • safety features and ratings
  • functional features relating to how the fan is made
  • operating features for ease of use
  • initial and ongoing costs

3. How the fan is setup is critical for effective cooling. Your set-up may involve some trial and error to determine the settings and placement that work best for you. Any fan can provide more cooling, use less energy and be safest when it’s set up well.

Other Outdoor Cooling Methods

Take a look at our comparison page to learn which cooling methods may be best for you.

Outdoor fans work well on their own and combine well with misting systems for added cooling effect. Misting fans are a clear example of how misting systems work with another cooling method to maximize cooling.

Swamp coolers (desert coolers) use a similar technology as misting systems, but in a contained unit.

Outdoor shades are a nearly universal solution that can add to the cooling effect of all cooling solutions.

Portable air conditioners can be the best outdoor cooling solution for special circumstances.