CFM, or cubic feet per minute, is a measure of air flow, indicating how much air a fan can ventilate per minute. For example, a 1,000 CFM fan can remove all air from a box that is 10 ft. x 10 ft. x 10 ft. in one minute. Your range hood should be capable of completely cycling the air in your kitchen every 4 minutes for a total of 15 times per hour. To determine the air flow needed for your kitchen:
Measure the total cubic feet of your kitchen by multiplying length x width x height.
Example: 10 ft. x 15 ft. x 8 ft. = 1200 cubic feet
Divide the total cubic feet by 4 to get the required CFM rating
Example: 1200/4 = 300 CFM
You can also determine the air flow needed for your kitchen based on your stovetop:
Electric stovetops need 100 CFM per 10" of width.
Example: 30"W/10" = 3
3 x 100 = 300 CFM
For gas stovetops divide the total BTUs by 100. The BTU is the measure of how much heat emits from the unit. This information is provided by the manufacturer and can be found in the item description (on web pages), or in the literature included with the stovetop.
Example: 15,000 BTU/100 = 150 CFM.
Because every situation is different, the CFM required may vary. If you are someone who cooks frequently, you might consider going higher than the minimum when selecting your range hood. It is better to have a higher CFM than not enough. The higher CFM would result in more air being exhausted, and cleaned faster.
To read more information about selecting the right range hood for your kitchen, check out our Range Hood Buying Guide.