The Bathroom Exhaust Fan Buyer Guide


Looking to upgrade your bathroom experience? A new exhaust fan might just do the trick, and at SUPPLY.com, we’ve got you covered! But first, check out our bathroom exhaust fan buyer guide for everything you need to consider before making the purchase.

The Basics

Bathroom exhaust fans (also called ventilation fans) are embedded in either the ceiling or the wall of your bathroom, for the purpose of venting humid or odorous air from the room to the outside of the home. These fans can serve an enormous purpose if used correctly, especially in bathrooms without windows.

Most municipalities have laws that require ventilation fans be installed in a bathroom. We highly recommend installing a ventilation fan in the bathroom, regardless of the law in your town, for several reasons. Mainly, fans reduce the potential for mold to grow, keep the bathroom dry, and make a shared bathroom experience more pleasant for families and guests alike.


Exhaust fans should be first and foremost chosen based on the size of the bathroom they will be used in. The larger the room, the larger the fan needed. Fan size is measured in cubic feet per minute or CFM. The easiest way to determine the fan size needed is the “1 for 1 Rule”:

For every 1 square foot of room, you will need 1 cubic foot of fan

For example, an 8 x 10 room is 80 square feet, and therefore needs a fan of at least 80 CFM.

Common fan sizes are 50 CFM, 80 CFM, and 100 CFM. If your room’s square footage does not match a predetermined measurement, round up to ensure proper ventilation. A 90 square foot bathroom should have a fan of 100 CFMs, not 80. Do not include ceiling height in your CFM measurement.

Two hands holding a bathroom exhaust fan


The most common complaint about bathroom fans is that they are loud. This may be true…if you have an old, out of date fan.  Modern fans, on the other hand, are quiet yet effective.

The sound level of exhaust fans are measured in sones. The lower the sone level, the quieter the fan. To ensure you choose a fan that is barely audible, go with one rated at 2 sones or less.

Motion Sensors and Timers

Generally, ventilation fans are wired to a switch in the wall. This allows a person to control the fan at their leisure. The problem with this is many people forget to turn on the fan, especially after a shower when it is needed most. Bathrooms in businesses and offices can be even worse. The solution? A bathroom fan with a motion sensor and timer.

Exhaust fans with motion sensors and timers know when a person enters the bathroom and immediately turn on. Once the person leaves the bathroom, the fan continues to remove air for the amount of time set on the timer (usually 5 – 15 minutes). This ensures any humidity or smells will properly vacate the bathroom even after the person leaves. Homeowners can adjust the length of the timer depending on their preferences.

A yellow bathroom with 3 can lights in a rowLights

Many bathrooms, especially powder rooms, are very small and have very little ceiling space to sacrifice. Therefore a ventilation fan with a built-in light is a smart choice. Both LED and CFL options are available. LEDs are usually built into the fan and are unable to be changed; while this may seem like a downside, LEDs in the bathroom will last a lifetime if they are not left on all day, saving you the hassle of having to climb a ladder to change a light bulb. Both LED and CFL lights built into bathroom exhaust fans are eco-friendly and can lower your electric bill. Not too shabby for a bathroom fan!

Have recessed lights in your bathroom? The Panasonic Recessed ventilation fan has a canned light built right in. The air pulls in through the light leaving guests none the wiser that there is even a fan in the bathroom! Several can lights in a row (as seen in the photo on the left) are even better to disguise the fan and are a sophisticated way to illuminate your bathroom.

Damp-Rated Fans

An exhaust fan over the shower is a smart way to ensure humidity from the shower won’t cause mold. If you will be placing a ventilation fan above the shower, be sure it is damp-rated. If not, water and humidity can interfere with the fan’s wiring, causing it to break.


Multi-family dwellings like apartment buildings legally must have fire dampening insulation in between units. This insulation is usually placed in the ceiling between floors. Ventilation fans placed in these ceilings can disrupt the fire dampening, which can be a problem during inspections. In these instances, wall ventilation fans like the Panasonic Whisper Wall Fan installed close to (but not on) the ceiling can come in handy.

Ready for an exhaust fan? Shop SUPPLY.com today!