Kitchen Hood CFM Requirements: What You Need by Stove Type

What CFM Means and Why It Matters for Your Range Hood

CFM stands for cubic feet per minute, a measure of how much air your range hood moves in one minute. In practical terms, it tells you how quickly the hood can pull smoke, steam, grease, and odors away from your cooking surface and vent them outside. A hood with too low a CFM leaves your kitchen hazy and greasy; one with too high a CFM can be noisy and waste heated or cooled air.

The right CFM depends mainly on two factors: the type of stove you cook on and the heat output of its burners or elements. Gas burners produce combustion byproducts like carbon monoxide and nitrogen dioxide, so they need more ventilation than electric or induction cooktops, which generate no direct combustion. Your cooking style—whether you sear steak often or mostly simmer sauces—also shifts the number up or down.

Building codes and ventilation standards, such as those from the International Residential Code (IRC) and the Home Ventilating Institute (HVI), offer general guidelines. For gas ranges, many codes require at least 100 CFM per 10,000 BTUs of burner output. For electric and induction, a simpler rule based on kitchen size often applies. You'll see both approaches below, along with a worked example that ties them together.

The BTU Rule for Gas Stoves: A Step-by-Step Calculation

For gas ranges, the most common starting point is the BTU rule: total the BTU output of all your burners, then divide by 100 to get a base CFM. For example, a typical 30-inch gas range might have four burners rated at 5,000, 10,000, 12,000, and 15,000 BTUs, plus a grill or griddle. Adding those gives 42,000 BTUs. Divide by 100, and you get 420 CFM as a baseline.

This number assumes you use the hood occasionally and don't do heavy searing or frying. If you cook with high heat often—say, wok cooking or frequent pan-searing—add 50 to 100 CFM to account for the extra smoke and steam. Some guidelines also suggest adding 50 CFM for every 10,000 BTUs over 40,000, but the simpler division method is a solid starting point for most home kitchens.

One caveat: the BTU rule assumes your hood is ducted to the outside. If you have a recirculating hood (one that filters air and sends it back into the kitchen), you'll need a higher CFM because the carbon filter reduces airflow efficiency. In that case, multiply the base CFM by 1.5, or look for a hood rated specifically for recirculating use.

Electric and Induction Stoves: The Room-Size Method

Electric and induction cooktops don't burn fuel, so they produce less airborne contamination. The main concern is steam, grease, and odors from cooking, which means the hood's job is more about capturing particulates than removing combustion gases. For these stoves, the simplest method is based on your kitchen's volume.

The standard formula is: (kitchen length × width × height) × 4, then divide by 60 to get CFM. The factor of 4 represents the number of times the hood should exchange the kitchen's air per hour. For example, a 10-foot by 12-foot kitchen with 8-foot ceilings has a volume of 960 cubic feet. Multiply by 4 to get 3,840, then divide by 60, giving 64 CFM. Round up to 100 CFM for a standard hood, since most models start around that rating.

This method works for both electric and induction, but induction cooks often prefer a slightly higher CFM because they tend to sear at very high temperatures. If you regularly use a cast-iron skillet on high heat, add 50 CFM to the room-based number. Also, if your kitchen is part of an open-plan living area, include the adjacent space in your volume calculation—otherwise, you'll undershoot the required airflow.

Worked Example: A 30-Inch Gas Range in a Family Kitchen

Let's walk through a real scenario to show how these rules combine. Suppose you have a 30-inch gas range with four burners rated at 5,000, 10,000, 12,000, and 15,000 BTUs, totaling 42,000 BTUs. Using the BTU rule, you divide by 100 to get 420 CFM. Now, you also have a 10-foot by 14-foot kitchen with 9-foot ceilings, and it opens to a dining area, so the total open space is about 10 by 20 feet. The kitchen volume is 10 × 14 × 9 = 1,260 cubic feet, but with the open dining area, you'd use 10 × 20 × 9 = 1,800 cubic feet.

For the room-size method, you'd calculate 1,800 × 4 = 7,200, then divide by 60 to get 120 CFM. That's much lower than the 420 CFM from the BTU rule. When the two methods conflict, the BTU rule should take priority for gas stoves because it directly accounts for the combustion byproducts. So your baseline is 420 CFM. Since you sear steaks twice a week, add 50 CFM, bringing the total to 470 CFM.

In this case, you'd look for a hood rated at 500 CFM (rounding up to the nearest standard size). A 400 CFM hood would be too weak, and a 600 CFM model would work but might be overkill and noisier. Also check the hood's noise rating in sones—a 500 CFM hood with a sone rating under 4 is quiet enough for normal conversation. If you have a gas stove, make sure the hood is vented outside; recirculating models would require roughly 700 CFM to compensate for filter resistance, which is impractical for most homes.

Adjusting for Duct Length, Bends, and Makeup Air

The CFM numbers above assume a short, straight duct run to the outside. In reality, every 90-degree bend in the ductwork reduces airflow by about 10%, and every foot of flexible duct adds more resistance than rigid metal pipe. If your hood vents through a long run—say, 20 feet or more—or has multiple elbows, you need to increase the rated CFM to compensate. A common rule is to add 10% for each 90-degree bend and 5% for each 45-degree bend, plus a small penalty for duct length.

High-CFM hoods (typically above 400 CFM) also require makeup air. When the hood exhausts air, it creates negative pressure in your home, which can pull combustion gases back down the flue of a gas furnace or water heater. Building codes in many areas mandate a makeup air damper that opens when the hood runs above 400 CFM. Check your local codes; a qualified HVAC contractor can install a barometric damper or an active makeup air system.

For most home cooks, a 400 to 600 CFM hood is sufficient for gas ranges up to 36 inches wide, while electric and induction cooktops rarely need more than 300 CFM. If you have a commercial-style gas range with 60,000 BTUs or more, you may need 600 to 900 CFM, but that's rare in residential kitchens. Always measure your duct path and account for bends before finalizing the CFM rating, and if you're unsure, consult a ventilation professional who can perform a load calculation.