Let’s talk about how many CFM you need to keep your kitchen clean and free of lingering smells. The ventilation power of your range hood is measured in cubic feet per minute (CFM). CFM is how many cubic feet of air the range hood exhausts every minute at full speed. Simply put, the higher the CFM, the more air the hood vents out of your kitchen. To vent cooking exhaust from your kitchen efficiently, we recommend a range hood with at least 600 CFM. Range hoods over electric and gas cooktops, along with outdoor grills, require different CFM ratings.
Simply multiply the width of your stove by 10 to get the appropriate CFM for your range hood. The amount of heat emitted from a gas cooktop is measured in British thermal units (BTUs).
BTUs describe the amount of heat required to raise the temperature of a pound of water by one degree Fahrenheit. To determine the CFM of a hood over a gas range, add up the BTU output of each burner and divide it by 100. Because gas stoves generate more concentrated fumes, it is better to err on the side of caution and choose a higher CFM. Remember, your outdoor grill has higher BTUs than an indoor cooktop.
Calculate your outdoor grill’s minimum CFM needs the same way as your gas stove: determine the total BTUs and divide by 100. 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’ tall = 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.
Finally, take the larger number and use it as the minimum CFM requirement for your new 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.
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, go with a higher CFM range hood. If you are building a new kitchen, you’ll need to install proper ducting for your vent hood.
For older, less powerful range hoods, ducting sizes tend to be four to six inches in diameter. However, higher CFM ratings require larger diameters of eight to 10 inches. Without an adequate size duct, a higher-CFM blower will encounter too much air resistance to work effectively.
Smoke and steam will stay in your kitchen, as well as cooking odors, which is not ideal. But if the size of your duct matches your ventilation power, your kitchen exhaust fan will do its job properly and quietly. A good rule of thumb for estimating duct diameter and CFM requirements is: Besides the duct diameter, the length, the number of turns and whether you have a roof cap all influence CFM.
Be sure that this answer lies within the higher end of the recommended CFM based on the chart below. Frequent cooks will require more CFM to vent the dirty air and smoke outside their home and keep the space free of strong odors.
Keep in mind that other factors like length of ductwork, number of elbows, and the size of your kitchen may impact the CFM. A higher CFM is ideal because it allows you to cook a wider variety of foods compared to weaker hoods, while keeping your kitchen air clean and fresh.
Have a hood with small diameter ductwork that won’t support a higher CFM
Run your AC and heater often – the cool and warm air will leave your home, which is your money going out the door
If your range hood lacks variable speeds, you will have no choice but to run it at a higher cubic feet per minute than you might need when you’re cooking less intensively. This means you will be removing more air from your kitchen than is necessary, potentially causing you to lose the heat you want in your home.
You’ll also lose the money it costs to run the hood at its max speed. If your hood isn’t sized properly, a higher CFM will not necessarily help you eliminate all the fumes. As mentioned above, your ductwork impacts the capacity of a high power blower to remove air.
Every situation is different, but you’ll never regret buying a more powerful fan.
Keep in mind that you won’t be running it on its max speed all the time. There’s a commonly held myth that you need makeup air for range hoods that are more powerful than around 300 or 400 CFM.
If it is not at least six inches larger than your range, you won’t be able to maximize the power of your hood fan. Range hoods need to have the proper amount of overhang and depth for them to work effectively.
The further your hood extends past the edges of your cooktop, the better – particularly if you have an island range. If you have an outdoor kitchen, aim for your hood to extend six to 12 inches past the cooktop.
Your vent hood must be installed between 28” to 36” inches away from the cooktop to maximize your ventilation power. With a larger capacity, you will be able to run your hood at lower and quieter speeds as well.
Proline’s stainless steel baffle filters capture grease efficiently and they are dishwasher-safe. Now that you’ve calculated the minimum requirements for your range hood’s CFM, remember that, in most cases, it’s a good idea to scale it up.
Scaling up is especially beneficial for island range hoods, which are exposed to your kitchen air on all sides. For this reason, wall mount range hoods don’t need as much CFM to keep your air clean.
That being said, most bathroom fans and range hoods are measured in CFM while air tools use SCFM. You can find a powerful, professional-quality leaf blower at 300 CFM on Amazon.
If you own several types of air tools, make sure that your compressor can power the one that requires the most CFM. To calculate range hood CFM, divide the total BTUs produced by your cooktop by 100.
More cubic feet per minute is almost always better since you can run your range hood on lower speeds if you don’t use the max power often.
Range hoods from big box stores do not have enough power to vent all the smoke from your cooking space and are not made with high-quality materials.