Best Bathroom Exhaust Fans of 2025

A bathroom exhaust fan works by pulling in air from the bathroom and sending it outside via a duct that runs through the ceiling or wall. So, a good exhaust fan relies largely on good airflow. Good airflow, in turn, depends on the ductwork in your bathroom and the speed of the fan.

The more bends in the duct, the more resistance there will be to the airflow—so, to a large extent, the effectiveness of your exhaust fan will depend on the shape of the ductwork in your home. 

The size of your duct also matters. Bathroom exhaust fans are designed to fit a particular duct size. Generally, fans built for larger air ducts produce better airflow. Newer bathrooms tend to have vents with 4-inch ducts or larger, while older bathroom vents tend to have 3-inch ducts. You can renovate to upgrade your duct size, though that will require professionals and a chunk of money. More important, if you have a smaller bathroom (around 50 square feet or smaller), that smaller duct size—and the fans built for it—may work quite effectively for you anyway.

As for a fan’s speed, it’s a measurement of airflow velocity in CFM. Most fans on the market run at only one speed. While it may seem logical that a fan running at a higher speed trumps a fan at a lower speed, you might not see that big a difference in effectiveness between the two, especially in a smaller bathroom. A higher fan speed could also be noisier.