What Is CFM & How Much Do I Need for My Range Hood?

by Pete Lader March 12, 2022

Source: brizmaker / Shutterstock.com

The range hood is one of the most critical elements of your kitchen. It absorbs smoke, heat, steam, odors and other airborne particles generated during the cooking process. The role of a range hood is to improve your kitchen’s air quality and reduce the amount of time spent cleaning your kitchen surfaces. However, not all range hoods are created equal. The primary way to differentiate range hoods is to check their ventilation power, measured in Cubic Feet per Minute (CFM). Learn about CFM and how to select the best CFM value for your kitchen.

oven with large range hood above

Source: Jodie Johnson / Shutterstock.com

CFM Explained

Range hoods are fans equipped with air filters, similar to other HVAC appliances. They are categorized primarily by their ventilation power, measured in CFM.

The higher the CFM value, the more air your range hood can absorb and vent out of your kitchen when running at full speed. Range hoods must be sufficiently powerful to cycle the air around the cooking area (typically above kitchen ranges) reasonably quickly without being excessively noisy.

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How to Find the Ideal CFM Value

Whether you are looking for a replacement range hood or shopping for complete kitchen appliance packages, you must determine the ideal CFM value for your kitchen. Multiple factors contribute to the ideal CFM: the range hood’s type, the power output of your stove and the size of your kitchen.

Range hood type

If the range hood you need is a wall-mounted or under-cabinet model, measure the width of your cooktop in feet and multiply the result by 100.

  • Example: If your cooktop is 36" (3 feet) wide, you need a range hood with a minimum of 300 CFM (3 x 100).

If your range hood is an island-type model designed to fit above a kitchen island stove, the minimum CFM value you need is 150, multiplied by the width of your cooktop in feet. The extra power is necessary due to the open-ended nature of island stoves.

  • Example: If your island cooktop is 36" (3.5 feet) wide, your island range hood must be at least 525 CFM (3.5 x 150).

Stove type and output

Gas-powered stovetops generate more heat than their electric counterparts, requiring a different CFM calculation method. The heat output of a gas stove is measured in British Thermal Units (BTU). One BTU corresponds to the amount of energy required to heat one lb. of water up by one°F at sea level. Each burner has a different BTU rating, typically listed in the stove’s user manual.

When looking for range hoods for a gas stove, the best CFM value depends on the stove’s combined BTU ratings. Most burners range between 5,000 BTU and 15,000 BTU; a typical four-burner stove usually has a combined BTU value of 40,000 to 50,000 BTU. To calculate a specific model’s ideal CFM, add the BTUs for all burners to obtain the stove’s combined BTU value and divide the result by 100. You’ll need at least 100 CFM for every 10,000 BTUs to power your range hood.

  • Example: If your gas-powered four-burner stove has a combined BTU value of 42,500, your range hood must be at least 425 CFM (42,500 / 100).
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Room volume

Although a range hood is meant primarily to cycle the air around the cooking area, it must have enough power to process the air in the entire kitchen in less than four minutes (or 15 times per hour). The higher the volume in your kitchen, the more powerful your range hood needs to be.

To calculate your kitchen’s volume in cubic feet, multiply the room’s length, width and ceiling height. Alternatively, multiply the floor area by the ceiling height. To obtain the best CFM, divide the number of cubic feet by four.

  • According to the National Kitchen & Bath Association, the average kitchen is approximately 13' x 13', or 169 ft². Assuming a ceiling height of 8', the volume is about 1,352 ft³. So, the ideal range hood for a kitchen of this size is 338 CFM (1,352 / 4).

kitchen with industrial vent

Source: Image Supply / Shutterstock.com

How to Decide Which CFM Value I Need

The easiest way to pick a target CFM value is to use all three calculation methods and use the highest value obtained. This value will be your target value: the minimum amount of CFM your range hood must produce. When shopping for range hoods or complete kitchen appliance packages, such as the Thor series, select a range hood model with a CFM value that matches or exceeds your target value. To avoid generating excessive noise, ensure the model you choose does not exceed the target value by more than 10-15%.

Wall Mount Range Hoods:

Under Cabinet Range Hoods:

Island Range Hoods:

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