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Fans Add Comfort While Improving Air Quality


Bathroom fans add comfort and improve air quality by venting moist air quickly to the outside. 
Some models do so very quietly as well. They eliminate problems associated with high humidity like mold and mildew growth, steamy mirrors and peeling wallpaper and paint. The Home Depot has a wide selection of bathroom fans, from fan-only units to models with lights, nightlights and heaters as well as decorative and extra quiet models.
This guide will help you understand what you should look for in a fan, how to choose the right size, and the extra touches that can give your bathroom spa-like comfort and style. 



A fan’s ability to move air is measured in Cubic Feet per Minute, or CFM.

• Most fans are rated anywhere from about 50 CFM to 110 CFM
• The bigger your bathroom, the higher the CFM rating needed
• Experts recommend a fan should have a CFM rating high enough to replace the air in your bathroom 
  8 times per hour

Sizing Your Fan

More is better; the larger the CFM the more quickly humidity is removed. You can estimate the minimum number of CFMs your bathroom requires using the rules of thumb guidelines below. These estimates are for bathrooms with 8' ceilings.

Rules of Thumb

Bathrooms under 50 SF 50 CFM fan
Bathrooms over 50 SF Select a fan that can move at least 1 CFM per square foot of bathroom area. For example, an 80 square foot bathroom will need a fan rated at 80 CFM.

To calculate the minimum CFMs required for larger bathrooms, use this formula:
        Length X Width X Height X 0.13 = Minimum CFM rating  


Your bathroom is 6’ long by 8’ wide with a 10’ high ceiling:  
6 X 8 X 10 = 480 X 0.13 = 63  

The minimum CFM rating for your bath fan is 63 CFMs.  
This calculation assumes that you have one sink and one shower head. More shower heads, for example, would increase the need for a stronger air flow.


The amount of noise a fan makes is an important consideration in choosing your fan. The industry standard for measuring the amount of sound a fan makes when it operates is called “sones”. One sone is equivalent to the sound of quiet refrigerator. The lower the sone rating, the quieter the fan will be. A quiet bathroom fan will be rated at about 1.5 sones or less.


If you are going to install a fan in the bathroom for the first time, you may want to consider placing it where your light fixture currently is and installing a model with a light.
This allows you to use the existing wiring and switch, depending on your fan’s features and how much control you want over the individual functions. Some fan/light combination models have decorative designs and finishes that look stylish simply as light fixtures. Choose a model that uses one bulb or two, depending on how much light you need.
Remember that you’ll need to wire the light and fan separately in order for to control them independently. Make sure to get a combination switch that has 2 or 3 controls on it in order for this to occur.


Proper ducting is an important aspect of your fan’s effectiveness. Fans in top story bathrooms are ducted through the attic to the outside through the roof, wall or soffits.
Fans in bathrooms in the first story of a multi-story home are vented through the side of the house. Regardless of location, the moist air needs to be exhausted outside. Never vent a fan directly into an attic.
If you are upgrading a fan to a higher performance model, the diameter of the duct connector on the new housing may be larger than the size of your existing duct. To maximize performance, try to upgrade your duct diameter to match the new fan.

Features to Consider

Night Light

A night light helps you move safely in the dark and is helpful for small children and elderly people.


A built-in heater provides convenient, instant heat after a shower or bath. Options include fan-forced heat or infrared radiant bulbs.


Experts recommend you run your fan for 20 minutes after a shower or bath. A timer makes this easy by turning your fan off automatically.


Complement the look of your bathroom with fan/light combinations that feature decorative styles and finishes.