Why do fans mostly have 3 blades?

fans have 3 blades

You may have wondered but why most fans feature 3 blades. Many people do not know the science behind having fans in our houses that only have 3 blades. Rarely will you see fans with less than three blades or more than three blades in our houses? Then the reasons remain why three blades.

Do not scratch your head anymore as we have researched for you and we have an answer as to why there are three blades in a home-based fan rather than any other number of blades. Read on as we dig deeper into this.

The question?

Every person who notices three blades on all fans most of the time would enquire the aerodynamic laws at play to stick with 3 blades. On the other hand, thinking of fluid mechanics comes into their heads. That is if you went to a physics class. Additionally, the popular principle that can account in this scenario would be Bernoulli’s principle. But how does it play?

While all these questions linger in the mind of a person, especially one inclined to physics, it is very sad that none has the perfect explanation for finding 3 blades in every fan they encounter.

How many blades should a fan have?

Fans could have as many fans as there can be. For instance, an airplane propeller fan features a single blade fan that is used at propelling the airplane while it is flying. On the other hand, you may find home fans with either 2 or 3 blades used for a cooling effect.

Additionally, in big industrial buildings, what you find at the top of the building are cooling fans that feature many blades in them. As such the question remains why have 3 blades?

Why have 3 blades

One of the explanations for having 3 blades on a home fan is foremost because of the model as well as aesthetics.

To start with, fans serve to create airflow around the room thus creating a cooling effect to the room. However, while doing this, it must not create unnecessary noise to the user. Thus must operate at minimal noise.

To propel the blades is a shaft run by a motor. For a fan for home use, the shaft features a moderate speed for safety purposes. These low speeds on the other hand help in the reduction of the noise that emanates from high speeds.

Since you can have any number of blades, having one blade causes an imbalance of the shaft thus would lead to wobbling. However, on the other hand, two blades would require the opposite arrangement. For 3 blades, a variation of 120 degrees is required.

The science

Of course, we would end up here. Since we have seen there can be any number of blades on a fan, the number of the blades is a factor of the application of the fan. This entails the volume of air to be moved coupled with the required pressure the movement should occur.

For high volumes of air to be moved, low pressure is effected. This is the scenario in most of our rooms. The resultant effect is a cooling breeze. Thus fans with 3 blades offer the perfect solution in our homes.

On the other hand, for high pressures, the resultant effects are a high draft force as well as increased noise. No one wants this in their houses. Thus for higher pressures, several blades are applicable to run at very high speeds.

The reduction of noise produced by such fans happens through a case that encompasses the blades. Additionally, the fan features placement at a distance away from people. Raised fans in cons situated high in industrial buildings form a perfect example.

Additionally, it is at three blades that all factors at play in the production of the fan seem to be at optimum. These include the size of the blades, the number of the blades angles and their pitch as well as the speed delivered by the rotor. To top it all, the cost of manufacturing as well as the power cost when in use form the reason for finding 3 blades in a fan.


Fans feature different blades depending on their purpose. In our case, all we need is a cooling breeze in our rooms. As such, the optimum number of blades to cause the cooling effect falls at 3 blades rather than many blades. Additionally, this falls as the most cost-effective way to provide a good cooling effect to your home.

You may check it out: 

Leave a Reply

Your email address will not be published. Required fields are marked *