• Proline Range Hoods

How Many CFM's Do I Need For My Range Hood?


This is one of the most common questions we are asked here at Proline. Let’s talk about CFM requirements and how to calculate the CFM you need to make sure you’re keeping your kitchen clean and free of lingering smells and harmful fumes.


The ventilation power of your range hood is measured in cubic feet per minute (CFM). This refers to how many cubic feet of air the range hood is exhausting for every minute of operation at full speed. Simply put, the higher the CFM, the more air the hood can remove.


To determine how much CFM you need for your range hood, consider the following:

  1. How often do you cook?

  2. What cooking style(s) do you like?

  3. Is your range gas or electric?

  4. How many BTUs is your kitchen range?

  5. How wide is your range hood?

  6. How long is your ductwork?

There is no ideal range hood CFM, but instead, an appropriate CFM based on your cooking style and habits in the kitchen. The best range hood is different for everyone and depends not only on your cooktop but on your cooking and lifestyle as well.


Table of Contents

  • 1. Type of Range and Output

  • 2. Size of Your Kitchen

  • 3. Cooking Routines

  • 4. Ductwork

  • How do you calculate CFM for a range hood?

  • How many CFM do I need for a 36” gas range?

  • Is 400 CFM enough for my range hood?

  • Is it better to have a higher CFM?

  • Do I need makeup air for my range hood?

  • What is the minimum duct size for a range hood?

  • How many CFM do I need for my range hood? – Some Other Considerations


1. Type of Range and Output

Range hoods over electric and gas cooktops, along with outdoor grills, require different amounts of CFM.


Electric

The rule for determining the minimum range hood CFM for electric ranges is determined by the width of your range. On average, you need roughly 100 CFM for every 10” width of your electric range. For example, if your cooktop is 36”, this calls for at least 360 CFM.


Gas

Gas ranges produce a lot more heat and fumes compared to an electric range so their CFM demands are higher. The amount of heat emitted from a gas cooktop is measured in British thermal units (BTUs).


This is the amount of heat required to raise the temperature of a pound of water by one degree Fahrenheit. Burners range from 400 BTUs to 18,000 BTUs, but most will fall somewhere in between.

The rule for establishing a gas range’s minimum CFM requirement is to add up the BTU output of each burner and divide it by 100.


For example, if you had two burners that put out 10,000 BTUs each and two burners that put out 15,000 BTUs each, your total BTUs for your stovetop would be 50,000. 50,000 divided by 100 equals 500 CFM or more.


This answer is a minimum requirement. Because gas stoves generate more concentrated fumes, it is better to err on the side of caution and choose a higher CFM.


Outdoor Grills

Remember, your outdoor grill has higher BTUs than indoor cooktops and may have side burners and other equipment that produce more fumes. Take it all into account when calculating the CFM for your outdoor range hood.


Calculate your outdoor grill’s minimum CFM needs the same way as your gas stove: determine the total BTUs and divide by 100.


2. Size of Your Kitchen


Ready to really geek out? When shopping for a range hood, it’s important to understand how the volume of your kitchen affects your range hood CFM. Larger kitchens will need to move more smoke and unwanted air to keep the air clean and harsh cooking odors at bay.


So, with a greater kitchen volume, you require more ventilation power. Once you’ve measured the size of your kitchen, you can calculate the CFM using the following formula.


First, determine the volume of your kitchen.

To calculate your kitchen’s size in cubic feet, multiply the length by the width and height.

For example, your kitchen is 18’ long x 14’ wide x 9’ ceiling height = 2,268 cubic feet.


Now, as an accepted rule for ventilation, a range hood needs to have the power to exchange your kitchen’s air 15 times per hour. To get the number of cubic feet moved per hour, multiply your kitchen’s cubic feet by the air exchanges per hour.


For example, 2,268 cubic feet x 15 air exchanges = 34,020 cubic feet per hour.


Next divide by minutes in an hour. 34,020 cubic feet ÷ 60 minutes per hour = 567.


Or, you can also simply divide the volume of your kitchen by 4 as every 4 minutes, your air needs to be exchanged. 2,268 cubic feet ÷ 4 minutes = 567. In this example, you’ll want a minimum of 567 CFM for this size of the kitchen. Next, calculate the CFM requirements for your cooktop (total BTUs/100) and compare that to the number you calculated for the volume of your kitchen.

Finally, take the number that is larger and use it as the minimum CFM requirement for your new range hood.


3. Cooking Routines

Your habits in the kitchen can influence whether or not you opt for a higher CFM kitchen range hood. Ask yourself a few questions to figure out what kind of routines you have and whether your unique cooking situation requires more powerful ventilation.

Frequency

How often do you cook? Do you make all your meals on your cooktop? Do you use all the burners at once?


Types of Foods

What kinds of foods do you like to cook? Do you cook a lot of fish and other foods with a strong odor?


Styles of Cooking

What styles of cooking do you prefer? Do you love to cook greasy foods? Do you fry foods on high heat? Or do you use a lot of oil? Do you regularly steam foods?


Are you a fan of Asian cooking? Do you cook fajitas, pizza, or other similar foods that produce a lot of smoke?


If you enjoy using your stovetop frequently or like to cook with fish and spicy foods or prepare meals that require high heat such as wok style cooking, be sure to factor this into your CFM requirements.


There isn’t necessarily a calculation for CFM based on cooking habits, but you should consider choosing a higher power blower if you often engage in more intense cooking routines.


4. Ductwork