What size bathroom fan do i need

What Size Bathroom Fan Do I Need

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Nothing beats a refreshing shower in a clean and spa-like bathroom. But do you know the secret of keeping your bathroom free from foul odors and bacteria? Yes, that’s the white grille mounted on the ceiling or wall, which is commonly called a bathroom fan. This electrically powered appliance is an important addition to every bathroom because it is designed to improve airflow and reduce excess humidity. Overall, it helps in making your bathroom a safe place for your family by preventing the accumulation of bacteria or mildew.

You might be asking yourself, “What size bathroom fan do I need?” Fret not. If you are looking to replace your broken bathroom fan and do not know how to find the right one, this article is for you. Here, you will find out how you will know the right size of bathroom fan to choose as well as the other important buying factors to consider.

What Size Bathroom Fan Do I Need?

The most common question that people ask when buying a new unit is what size bathroom fan do I need? That is because bathroom fans come in different shapes and sizes, so choosing has become somehow confusing. Aside from this, it is paramount for you to get the right size of bathroom fan to ensure that your restroom will be well ventilated.

Bathroom fan sizes are based on its airflow capacity that is measured in CFM or cubic feet per minute. The general rule of sizing according to Home Ventilating Institute (HIV) is 1 square foot equals to 1 CFM. For example, your bathroom is 100 square feet, the right bathroom fan for you should, therefore, has 100 CFM. However, you should also take note that having toilet, shower, and other fixtures in the bathroom mean more wet area. So, HIV also recommends adding 50 CFMs for every fixture, especially in public and communal bathrooms.


Bath fans are mostly seen installed in the ceiling, but you can also find models that are mounted on the wall. Whichever design you prefer, you should remember that the vent part of the fan should exhaust the moisture out of your home. If you have an attic above the bathroom ceiling, then it might not be ideal to mount the bath fan on that part. Another thing to take note is the size of the duct adapter that will be connected to your house’s ductwork. Some models are easy to install by merely following the user manual. However, other models may need professional assistance that can perform complicated wiring procedures.

Added features

Today, manufacturers have added a variety of features to extend the functionality of the bath fans. Aside from fans, they also have light bulbs for extra brightness in the room. This can also replace the fixtures in the bathroom and save energy when needed. Others might integrate night lights and built-in heaters. The most advanced models have sensors that monitor the humidity and motion, turning on the fan when the room reaches a certain humidity level or when there is an action. It will then turn off when the humidity lessens.

Noise level

The loudness of the sound that the bathroom fan produces is measured in sones. If you like taking a rest while enjoying a steamy hot bath, then you would also want a bath fan that operates quietly, lest your peace will be disturbed. 1 sone is equivalent to a quiet sound of the refrigerator while 2 sones are obviously louder and more noticeable than that. There are models that are below 1 sone, producing whisper-silent noise. However, they are more expensive on the market. Bathroom fans producing sounds at 2 sones are ideal and more affordable. But no matter how cheap 5-sone fans are, do not choose them.


Bathroom fans have become more energy efficient today than they were before. The truth is, they are now 70% lower in consuming energy. The performance is still powerful but the consumption is less. It really won’t affect your utility bill when you add a bath fan, so it’s clearly a cost-effective option. What’s more is that bath fans are greener, too. They produce less or no harmful fumes that can potentially harm the environment. To ensure that your unit is cost-efficient, make sure that it is Energy Star certified.

About the Author Joe Borges