To power your range hood, **you need at least 100 CFM for every 10,000 BTUs of your stovetop**. For example, a 100,000 BTU stove needs at least a 1000 CFM range hood. For electric stoves, multiply the stove width by 10. So, for a 42” electric stove you want a range hood with at least 420 CFM.

A range hood fan should move a minimum of 100 CFM of air for every 12 inches of stove width. This means that if you have a stove that is 30 inches wide then you need a range hood with a fan that rotates at least 250 CFM of air.

For high-output gas ranges or cooktops, the minimum rate of 1 CFM of ventilation per 100 British thermal units (BTU) is recommended. For example, if your high-output burner output is 45,000 BTU, look for a range hood that provides 450 CFM to best clear the air. However, the higher the CFM, the louder the hood will be.

The suggested CFM requirements for cooktops: “Regular” gas cooktops output 40,000 BTU's. To calculate your gas stove's BTU, add the power of each burner and divide the total by 100. So a “regular” gas system would need a 300 CFM fan.

For gas cooking surfaces or range, a minimum ventilation level of 100 CFM (Cubic Feet per Minute) per 10,000 BTU is recommended. However, the hood must have a minimum of 500 CFM of ventilation power.

CFM is a 'ft^{3} per minute' unit. That's why we need to divide the total volume by 60; hence 4,800/60 = 80 CFM. Answer: You need an 80 CFM airflow (for 300 sq ft standard room and 2 ACH). Here's a neat CFM calculator that calculates CFM based on room area, ceiling height, and the number of air changes per hour (ACH).

7 Things to Consider When Buying a Range Hood

- Know Your Kitchen.
- Range Hood CFM.
- Range Hood Size.
- Noise Level.
- Exhaust Type – Vented & Non-Vented.
- Installation Time and Cost.
- Budget.

As a general rule of thumb, for the same 30” cooktop, you'll need a range hood with 375 CFM. While we've modeled on an average sized cooktop, your stove may be as narrow as 20 inches or as wide as a 60-inch commercial model. Measure or check the specs in your user manual to be sure.

If you have a gas range, install your range hood 24 to 36 inches above your cooktop. If you have an electric range, install your range hood 20 to 24 inches above your cooktop. If you have an outdoor grill, install your range hood 36 to 42 inches above your cooktop.

Measure the width of the area over the range or cooktop. Range hoods often come in 24", 30" or 36" widths. The hood should be at least as wide as the cooking surface, but preferably should be 6" wider.

Good CFM ranges from 4,000 to 5,000. Better ranges from 5,000 to 6,000. Best is over 6,000.

Your range hood should be deep enough to cover all rear and front burners to most effectively vent your cooking space. For most range hoods, you can plan on a depth of about 18" to 22" for full coverage. Downdraft vents typically require installation in a cabinet below that's at least 24" deep.

Look at the CFM of a fan at the expected maximum air resistance (static pressure). Exhaust fans with a higher CFM need to be more energy efficient. Find the horsepower rating to give you the most energy efficient operation. An underpowered motor will wear out too quickly and requires too frequent maintenance.

CFM means cubic feet of air moved per minute. Simply put, it's the amount of air a ventilation hood fan is capable of removing through its filter every minute.

How far can you vent a range hood? Your range hood duct should not exceed 30' for a straight run, 25' for a run with one elbow, and 20' for a run with two elbows. The shorter the duct, the better. If your ductwork is too long, your kitchen air may not reach the outside.

How far should a range hood stick out? A range hood should cover as much area above your stove top as possible. It is best to exceed on the sides by 3 inches each, but you cannot have a range hood protruding out over the stove. For a 30 inch stove (back to front) the range hood could be either 21 or 24”.

For example, for a 30” range, a 36” hood is ideal. Then, subtract 2” and you get 34”. So a 34” hood insert or larger is a great fit for a 30” range. For outdoor applications, go with an insert two sizes larger than your range.

The HVI recommends taking a stove's BTU rating and dividing it by 100 to find a minimum level. For example, a stove with a 30,000 BTU rating would require a kitchen hood with a capacity of at least 300 CFM. A kitchen range hood should be able to cycle the air out of the entire kitchen 15 times per hour.

Unvented range hoods do filter some grease and cooking odors from the air, but the general consensus is that they're nowhere near as effective. Nor do they remove heat and humidity, so they won't help keep your kitchen cool while you cook. Above: An industrial-style vent (made of ducting) draws air up and out.

It is More Expensive

Usually, kitchen range hoods are expensive. The price of range hoods depends on several factors such as the CFM rating, the special features it comes with as well as its mode of blowing. The stronger the range hood, the higher its CFM rating and this makes it even more expensive.

Best Range Hoods

- Best Down-Draft: Broan NuTone 36-Inch Elite Ducted Down Draft Range Hood.
- Best Ductless: Cosmo COS-668AS750 30-Inch Wall-Mount Range Hood.
- Best Budget: Broan-NuTone 413001 Ductless Range Hood.
- Best Island: Winflo 30-Inch H103C Series Convertible Island Range Hood.

Is a higher CFM better? A higher CFM is always better for your kitchen fan. You can always run a high CFM hood on lower settings. It provides great ventilation by moving a heavy amount of air per minute.

McNulty says if a range top or range is 30 inches from the back wall, specify a 21-inch-deep or even a 24-inch-deep hood -- or something greater, depending on the cooking requirements of the homeowner.