How to Choose a Bathroom Fan

Determine the rate at which you want the fan to be able to exchange the air in the room. This is measured in cubic feet per minute, or CFM. Calculate the volume of the bathroom, and divide it by the number of minutes you want to take to exchange the air in the room. This will give the needed CFM rating. For instance, if you want to exchange the air in a 600-cubic-foot bathroom every 8 minutes, choose a fan with a CFM rating of at least 75.

Consider the noise level you want your fan to run at. According to Old House Web, "The amount of noise a bath fan generates is measured in sones." A fan rated at 1 sone is comparable to a refrigerator, while 4 sones is about as loud as a television set. Quieter fans are generally more expensive. Select the quietest fan that is within your budget.

Research different activation methods. Older bathroom fans work from a simple on-off switch, or you can use a timer switch to run the fan for a specific length of time. More advanced fans can sense humidity and run only when the bathroom is damp or work from computerized controls that allow them to run automatically at specific times during the day.

Select a fan from a reputable company that offers a warranty. A quality product should last a long time, but a warranty is important in case your bathroom fan fails soon after you purchase it.