What is a range hood?
Updated August 2026
A range hood is the powered canopy above the cooktop that captures grease, smoke, steam, and combustion gases before they spread through the house. Two families exist, and they are not equivalent. A ducted hood pushes that air outdoors through 6-inch or 8-inch pipe. A recirculating hood pulls it through a grease screen and a charcoal filter, then blows it back into the kitchen, which handles odor and grease but leaves the moisture and the nitrogen dioxide from a gas burner in the room.
Where it is
It hangs 24–30 inches above an electric cooktop and 27–36 inches above gas, mounted under a cabinet, as a wall chimney, on a rack over an island, as an insert inside custom millwork, or built into an over-the-range microwave. To learn which type you own, drop the grease filters and look up: a duct collar heading into the wall or ceiling means ducted, while a slotted grille across the top front that blows air back at your face means recirculating. Confirm it from the yard by finding the wall or roof cap with its damper flap.
What it does
Capture is the whole point, and capture depends on airflow, width, and habit. Size by CFM: for gas, divide total burner output by 100, so a 60,000 BTU cooktop wants about 600 CFM; for electric, plan on 100 CFM per foot of width, so a 30-inch range wants 250–300 CFM. The hood should be at least as wide as the cooktop, and 3 inches wider on each side is better. Anything over 400 CFM often triggers a makeup-air requirement in the local code. The failure list is short and predictable: loaded filters strangle airflow, blower bearings start howling, the exterior damper sticks shut so the fan pushes against a closed flap, or grease keeps building until it is fuel sitting directly above a flame.
Maintenance
Degrease the metal mesh filters monthly, either on the dishwasher's hottest cycle or in a sink of hot water with dish soap and a quarter cup of baking soda for 15 minutes. Swap the charcoal filter in a recirculating unit every 3–6 months, at $20–50 a pair. Twice a year, wipe the blower wheel and housing and confirm the exterior damper swings free. Everything else lives on the range hood checklist, and a hood treated this way runs 10–15 years.
What it costs to replace
A replacement range hood runs $100–1,000 for the hood itself, plus $200–800 to run duct on a first install.
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Frequently asked questions
How many CFM does my range hood need?
For a gas cooktop, add up the burner BTU and divide by 100: 48,000 BTU calls for about 480 CFM. For electric or induction, use 100 CFM per foot of cooktop width, so 250–300 CFM covers a 30-inch range. Add roughly 10 percent for every elbow and every 10 feet of duct. Buy for how you actually cook; a hood rated 600 CFM that you run on low because it sounds like a jet is worse than a quiet 400.
Is a ductless range hood worth having?
It is better than nothing and clearly worse than ducted. The charcoal cartridge traps odor and the mesh catches grease, but the water vapor, heat, and combustion byproducts stay in the kitchen, which is why ductless kitchens fog windows and grow film on the cabinet doors. If you are stuck with one, replace the charcoal every 3–6 months, cook on the back burners, and crack a window on anything you sear.
Can I convert a recirculating hood to ducted?
Usually yes, if the run is short. Most under-cabinet hoods ship with a top and a rear duct knockout plus instructions for rotating the blower housing 90 degrees. The work is punching a 6-inch or 7-inch hole, running rigid pipe to an exterior wall, and fitting a capped vent with a damper, which is a $300–900 job in a straightforward wall and much more if the path crosses joists or a second story.
How high should a range hood be mounted?
Follow the manual first, since clearances are part of the fire listing. As a default, 24–30 inches above an electric or induction cooktop and 27–36 inches above gas, measured from the cooking surface to the bottom of the hood. Island hoods usually sit 30–36 inches up. Mounting higher looks airy and loses capture fast, because the plume spreads before it arrives; mounting lower risks head strikes and violates clearance on many gas ranges.