Range Hood CFM: How Much Ventilation Your Kitchen Needs

Most kitchens need somewhere between 250 and 600 cubic feet per minute of airflow at the hood, and the right range hood CFM for yours comes from three numbers you can find in ten minutes: the width of the cooktop, the total burner output if it runs on gas, and whether the hood hangs on a wall or over an island. A 30-inch electric range on a wall is well served at 300. A 36-inch gas range with six high-output burners wants 600 or more, and at that point the conversation stops being about the fan and starts being about the duct and the makeup air that has to come with it.

We sell wood range hoods finished to match the cabinets, and the blower inserts that go inside them, so we have this conversation every week with homeowners told to "just get the biggest one." That advice fails more often than it works: an oversized fan on a 6-inch duct is loud and moves less air than its label promises, and a system capable of more than 400 CFM can trigger a makeup-air requirement that adds a second system to the job.

Key Takeaways

• Gas: about 100 CFM per 10,000 BTU of total burner output. Electric or induction: about 10 CFM per inch of cooktop width. Island: about 1.5 times the wall-hood figure.
• Width beats power: a hood at least as wide as the cooktop (one size wider for gas), deep enough to cover the front burners and mounted 24 to 30 inches up catches more than a bigger fan.
• The duct decides delivered airflow: roughly 6-inch round up to about 400 CFM on a short run, 8-inch for a 600. Smooth rigid metal, as few elbows as possible.
• The 400 line: the model IRC (M1503.6) requires makeup air for a hood system capable of more than 400 CFM when the house has a fuel-burning appliance that is not direct-vent or power-vented inside its air barrier. States and cities amend this, so ask your building department.
• What we sell: Fabuwood Allure wood hood shells with a stainless liner (no blower included) and Broan-NuTone RHBB inserts at 250, 400 and 600 CFM. Ductwork, the cap, makeup air and installation come from your contractor.

What the Airflow Number Actually Measures

CFM stands for cubic feet per minute: the volume of air a blower pulls through the hood and pushes out of the house every minute (our CFM glossary entry has the one-line version). The figure on the box is almost never the figure you get in the kitchen. Three numbers hide behind every label:

• Maximum or "free-air" airflow: what the motor moves with nothing attached. Fabuwood lists its 600 CFM insert with a 650 CFM "max blower" figure.
• Certified airflow: the Home Ventilating Institute (HVI) certifies ratings under standardized conditions. It is the fairest figure for comparing products, and HVI warns that non-certified ratings are often inflated.
• Delivered airflow: what leaves your wall or roof cap after the filters, every elbow, the length of the run and the damper. On a long or undersized run it falls well below the certified figure.

Newer spec sheets also list capture efficiency, the share of the fumes the hood actually catches (tested under ASTM E3087). It matters because cooking puts fine particles into the air and gas burners add nitrogen dioxide and carbon monoxide. Lawrence Berkeley National Laboratory tested seven representative hoods and found capture efficiency ranging from less than 15 percent to more than 98 percent. Hoods meeting the ventilation standard caught about 80 percent or more from the back burners but only about 50 percent or more from the front. The researchers' free advice holds everywhere: run the hood whenever you cook, and use the back burners first.

Four Ways to Size the Blower

There is no single official formula for a home kitchen, just four rules of thumb that measure different things. Run them all and take the highest number the ductwork can physically support.

• Burner output (gas): add every burner's BTU rating, including a griddle or grill with its own burner, and divide by 100. The ratings are on the rating plate (behind the oven door or under the drip tray) and in the manual.
• Cooktop width (electric and induction): 300 for a 30-inch unit, 360 for 36 inches. Induction puts less waste heat into the room, but the food makes the same smoke, so treat this as a floor.
• Per linear foot: HVI's published guidance recommends 100 CFM per linear foot of range for a wall hood and 150 for an island (minimums 40 and 50). A 30-inch cooktop is 2.5 feet: 250 on a wall, 375 on an island. HVI adds that professional-style cooktops should follow the appliance maker's guidance.
• Room volume: a 12-by-14 kitchen with 9-foot ceilings is 1,512 cubic feet; × 15 air changes ÷ 60 = 378 CFM. Useful in closed kitchens, misleading in open plans.

Some calculators add a flat duct allowance (1 CFM per foot, 25 per elbow, 40 for the cap); the equivalent-length method below is more honest about bad elbows. Finally, check the code floor: the model IRC requires kitchen exhaust of at least 100 CFM intermittent or 25 CFM continuous (Table M1505.4.4). Some states set higher minimums or accept a capture-efficiency rating instead; every realistic result below clears the model-code floor comfortably.

Worked Sizing Table: Six Real Kitchens

Here is the calculator done by hand for the six situations we quote most. Burner ratings are example figures; swap in your own. "Our target" is what we would spec after weighing the methods against the duct the house can take.

• A: every method lands near 300. A 400 on its middle speed is quieter than a 250 flat out, but its listed maximum is 450, so read the makeup-air section if a gas furnace or water heater shares the house.
• B sits right on the line: a 400-rated blower fits, but "rated 400" and "capable of more than 400" are not always the same product.
• C: six burners are rarely all on high, so 600 through an 8-inch duct under a 42-inch hood usually performs well. 900 is justified for heavy searing or wok cooking, and brings makeup air with it.
• E needs a professional hood: 54 inches or wider, 900 CFM and up, dedicated makeup air. That is beyond the shells we sell (our widest is 48 inches).
• F cannot exhaust, so the number only describes air pushed through a charcoal filter: some grease and odor removed, no heat, moisture or combustion gases.

Capture Beats Raw Airflow: Width, Depth and Height

Airflow only matters if the smoke reaches the filters. A hot plume rises and spreads like an upside-down cone, so a hood that is too narrow, too shallow or too high lets the edges roll past no matter how strong the motor. Most "my hood doesn't work" complaints we hear are capture problems, not fan problems.

• Width: at least as wide as the cooking surface. For gas or regular searing, one size up so it overhangs about three inches a side: 36-inch over a 30-inch range, 42-inch over a 36-inch. Extra width costs far less than extra CFM and does more for capture.
• Depth: the front burners are the ones hoods miss, so a shallow under-cabinet unit loses them. The Fabuwood shells we sell run roughly 20 to 24 inches deep depending on style (Allure spec book), far deeper than a 12-inch wall cabinet.
• Mounting height: the Broan-NuTone installation guide for the PM400SSV and PM600SSV, whose published specs match Fabuwood's 400 and 600 inserts, puts the hood bottom 24 inches minimum to 30 inches maximum above the cooking surface. If your range manual demands more clearance to combustibles, the higher number wins. The guide also calls for a metal liner below 30 inches to protect the cabinetry; every Allure wood hood ships with a full stainless interior liner.
• Wall vs island: a wall steers the plume upward; an island hood gets no help, which is why HVI's rate jumps from 100 to 150 per foot and why an island hood should overhang on every side. Our island clearance guide covers the walkway side of a cooktop island.

Duct Size and Run Length: Where the Air Gets Lost

The duct decides whether a 600 CFM blower behaves like a 600 or a 350: never smaller than the blower's outlet, smooth rigid metal, as short and straight as the house allows. The model IRC requires cooking exhaust to discharge outdoors through a smooth, airtight duct of galvanized steel, stainless steel or copper with a backdraft damper (M1503.3 and M1503.4), and the Broan-NuTone guide says ducted units must always vent outdoors in metal duct only.

Air in a small duct has to move faster, and faster air means more friction, resistance and noise:

The Broan-NuTone guide lists 6-inch round, 3¼-by-10 rectangular and 8-inch round connections, with the 8-inch for the 600 model only. Buy the 600 and then reuse the old 6-inch duct, and you have paid for airflow the pipe cannot carry.

Count equivalent length, not just feet

Every fitting adds resistance equal to some length of straight pipe. BEST, a Broan-NuTone brand, publishes an equivalent-length estimator; these figures come from it:

A real route for a 600 CFM insert: 3 feet up, one 5-section 90° elbow, 12 feet of smooth 8-inch duct and a wall cap is 3 + 7 + 12 + 25 = 47 equivalent feet. The same path with a 3-section elbow, 4 feet of flex to dodge a pipe and a neck-down to a 6-inch cap is 3 + 17 + 8 + 10 + 5 + 25 = 68 equivalent feet: roughly 45% more resistance and a weaker, louder hood. Leave a straight section above the blower before the first elbow, and on a long run go up a duct size rather than a blower size.

The 400 CFM Line and Makeup Air

Every cubic foot the hood blows out has to be replaced. In a tight house, a big hood can pull the building into negative pressure, and replacement air may come backwards down the flue of a gas water heater or furnace, bringing combustion gases with it.

Section M1503.6 of the model International Residential Code (2021 and 2024) says, in substance: where a fuel-burning appliance that is neither direct-vent nor mechanical-draft vented sits inside the dwelling's air barrier, each exhaust system capable of more than 400 CFM needs makeup air at approximately the exhaust rate, discharged into the same room or one connected by permanent openings, through a damper that opens automatically when the hood runs.

1. The trigger is "more than 400." A system capable of exactly 400 does not trip it.
2. "Capable of" is the phrase to watch. Fabuwood's 400 CFM insert lists a 450 CFM maximum, and inspectors read that differently from town to town. Ask before you buy.
3. All-electric homes are generally outside the model-code trigger, though a tight house can still be starved for air.
4. States vary. Many adopt the IRC with amendments or older editions; some require makeup air only for the airflow above 400 or add exceptions for larger homes. Your permit office decides.

If you cross the line, the options are: stay at or under 400 (a well-ducted 400 under a wide, deep hood beats a poorly ducted 600); passive makeup air, an outdoor-air duct with a motorized damper interlocked to the hood (cheap, but untempered air in winter); active or tempered makeup air, an HVAC contractor's job; or a "code ready" blower. Fabuwood's 600 includes Code Ready Technology, and the matching Broan-NuTone guide says it can be capped at 400 or 300 CFM, only within the first 5 minutes after power-up, and the change cannot be reverted. Decide with your inspector before the circuit is energized.

Sones: How Loud Is Too Loud

A hood too loud to leave on does not get used. Sones are linear to the ear: 2 sones sounds twice as loud as 1; 1 sone is roughly a quiet refrigerator, 3 to 4 ordinary conversation. ASHRAE Standard 62.2, the residential ventilation standard many codes and programs build on, caps intermittent kitchen exhaust at 3 sones at a speed that still moves at least 100 CFM, which in practice means a usable low speed. Fabuwood publishes normal-speed ratings of 3 sones for the 250 insert, 1 sone for the 400 and 0.5 sone for the 600; maximum-speed ratings are not published. A bigger blower loafing at a middle setting, on a bigger duct, is quieter than a small one flat out.

Ducted vs Recirculating

A ducted hood removes air from the house. A recirculating hood pulls air through grease and charcoal filters and blows it back into the kitchen; HVI says plainly that nonducted, recirculating hoods provide no actual ventilation.

Recirculate only when ducting is genuinely impossible, and avoid it over gas. Fabuwood's spec book recommends venting all its hoods outside, and the model IRC allows a listed ductless hood only where the kitchen has other code-compliant ventilation. Grease a weak hood misses ends up on the doors above the range; our cabinet grease removal guide covers cleaning each finish safely.

What We Sell, and What You Buy Elsewhere

A wood hood is a cabinet-shop product and a blower is an appliance-shop product, and the two get confused constantly.

Every range hood in our catalog is a Fabuwood Allure wood hood finished to match the Allure collections. Each ships with a stainless steel interior liner that accepts Fabuwood's Broan-NuTone inserts, and the shell does not include a blower.

Several styles come in Timber or Walnut accent versions. The Euro, Farmhouse and Signature chimneys are removable and trimmable, the Curved Artisan's one-piece chimney trims by up to 12 inches, and the Arched hood (not offered in Luna) can have its depth changed through Fabuwood's custom-quote process. Prices move, so check the live hood listings; as of October 2026 a 36-inch shell in a standard finish runs from $2,418 (Arched) to $4,043 (Farmhouse) at our site price, and oak finishes cost more.

All three carry Broan-NuTone's one-year limited warranty and fit every Allure hood, except that the 250 is not offered for the 48-inch Arched (RHA483021). RHBB DCT, listed as "Duct Cover," is actually a recirculating kit: a charcoal filter, soffit grille, 90° stack boot, 7-inch round duct and 6-to-7-inch transition. Its replacement charcoal filter is RHBB FLTR. Fabuwood notes it is not responsible for improper blower selection or installation, so sizing is on the buyer and installer.

You source elsewhere: ductwork, the wall or roof cap and backdraft damper; makeup-air equipment if needed; the electrical circuit and installation by a qualified installer; and anything above 600 CFM, any island hood, or any hood wider than 48 inches (our shells are wall-mount only). If that is your kitchen, we will still design the cabinets around a third-party hood.

Planning the Cabinets Around the Hood

Once airflow and width are settled, the range hood becomes part of the cabinet layout:

• Hood width sets the upper gap. A 36-inch hood over a 30-inch range needs a 36-inch gap between the flanking wall cabinets, so those uppers run three inches narrower than the bases below, or a filler absorbs it. Decide the hood first and draw the uppers around it.
• The hood sits higher than the uppers. Uppers usually hang 54 inches off the floor (see our wall and tall cabinet guide); a hood 24 to 30 inches above a 36-inch counter lands at about 60 to 66 inches. Do not pull it down to line up.
• Finished sides and crown. A hood projects well past 12-inch uppers, so its sides show; Fabuwood specifies crown above the Arched hood, not on the face frame. The Allure spec book has dimension drawings, and our Allure series guide covers the matching doors.
• Ceiling and soffit height. Chimneys trim down, not up, so check stack height against a 10-foot ceiling before ordering.
• Duct route before style. A chimney hood suits a vertical run into the ceiling; a wall-mount hood on an exterior wall can often vent straight out the back, the best duct there is. Our kitchen layouts guide helps test moving the range to an outside wall.
• Sample the finish. The hood is often the largest painted or stained surface in the room; order a Fabuwood door sample.

If the hood is part of a full order, our cabinet buying checklist covers what to settle before you pay, how to order kitchen cabinets online in 5 steps walks through measuring to delivery, and the Fabuwood price list prices the rest of an Allure kitchen.

Frequently Asked Questions

What does CFM mean on a range hood?

Cubic feet per minute, the volume of air the blower moves out each minute. The printed figure is usually a maximum with little or no duct attached, so real airflow after filters, elbows and the cap is lower. Compare HVI-certified ratings.

Is 400 CFM enough for most kitchens?

For a 30-inch electric or induction cooktop on a wall, and many 30-inch gas ranges, yes, if the hood is at least as wide as the cooktop and the duct is short and smooth. It is marginal on 36-inch high-output gas ranges, islands and frequent searing or wok cooking.

Can a range hood be too powerful?

Yes. Beyond what the duct can carry, extra capacity mostly buys noise; above 400 CFM it can trigger makeup air; and in a tight house it can backdraft a gas water heater or furnace. A wider, deeper hood usually helps more than a bigger motor.

Do I need makeup air for a 600 CFM hood?

Under the model IRC, yes if the house has a fuel-burning appliance that is not direct-vent or power-vented inside its air barrier. All-electric homes are generally outside the trigger. States and cities amend the rule, so confirm locally. Fabuwood's 600 can be permanently capped at 400 or 300 CFM instead.

How many CFM do I need for a 36-inch gas range?

Add up the burners and divide by 100: about 600 for a typical 60,000 BTU range, about 900 for a 90,000 BTU six-burner professional model. Pair it with a 42-inch hood and an 8-inch duct, and raise makeup air early.

What size duct do I need for a range hood?

Never smaller than the blower's outlet: roughly 6-inch round (or 3¼ × 10) up to about 400 CFM on a short run, 8-inch for 600, 10-inch for 900 to 1,200. A 600 on 6-inch duct runs, but the air moves about 1.8 times faster than in 8-inch, so noise rises and delivered airflow drops.

Do your wood hoods come with a blower?

No. Each Fabuwood Allure hood ships as a finished shell with a stainless liner; the 250, 400 or 600 CFM insert is a separate item. Ductwork, the cap, makeup air, electrical work and installation come from your contractor.

How high above the cooktop should a range hood be?

The Broan-NuTone guide matching Fabuwood's 400 and 600 inserts specifies 24 to 30 inches from the cooking surface to the hood bottom. If your range manual requires more clearance to combustibles, that number governs.

Your Next Step

Send us the cooktop's width, fuel type and burner ratings with a rough floor plan, and our free design service will size the hood and insert, place the uppers around it, and return a 3D layout with an itemized quote, typically within 24–48 hours. For a budget number first, try the kitchen cabinet cost estimator, or browse finish-matched hoods in the Fabuwood Allure collection.

Questions about a specific kitchen? Use our contact page or call 609-900-3358. We will tell you which blower fits, and when the right hood for your range is one we do not carry.