# How many CFM do I need for an exhaust fan?

The rule of thumb is that you need at least 1 CFM per square foot of room area. To determine the square footage of your bathroom, multiply the length times the width. For example, if your bathroom is 6 feet wide and 9 feet long, its square footage is 54. Therefore, it should have a fan rated for at least 54 ?CFM.Click to see full answer. Keeping this in consideration, how do I calculate CFM for exhaust fans?In general, to calculate CFM for your industrial exhaust application, you need to know the total floor area of your space. With this number, divide it by multiply it by 0.1 to 1 to get you estimated CFM. For example, a 1000 square foot area may need a CFM exhaust fan of 1000*0.1=100 or 1000*1=1000.Similarly, how do I increase CFM on my exhaust fan? To determine the fan’s minimum cfm, divide your bathroom’s volume by 7.5. Go with a higher cfm if the duct run exceeds 20 feet or has more than one elbow. Also, put the fan on a timer so that it runs for at least 20 minutes after you finish showering and exhausts all the moisture. Also to know, how many CFM do I need for my bathroom fan? Most fans are rated from 50 to 110 CFM. For bathrooms 50 square feet and smaller, it is recommended you purchase a bath fan designed for small rooms, which will typically have a CFM range of 50-79. For bathrooms that are larger, select a fan that can move at least 1 CFM per square foot of room.How many CFM does it take to ventilate a room? HVI recommends that a whole-house comfort ventilator have a minimum capacity to provide approximately one complete air change every two minutes within the occupied area. Whole-house comfort ventilator. House area Capacity in CFM 1,000 square feet 3,000 CFM 2,000 square feet 6,000 CFM 3,000 square feet 9,000 CFM