Behind the Best 42 Inch Under Cabinet Range Hood, an Unsized Duct

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A 42-inch under cabinet range hood is the size most people buy for a 36-inch range. The extra six inches give three inches of overhang on each side, by our arithmetic, and that overhang catches smoke and steam that drift outwards from the outer burners. So the buyer of a 42-inch hood is usually cooking on a big range, and the listings know it. Nine of the ten hoods on this page claim between 900 and 1,200 CFM.

The tenth is the odd one out, and it is the best-selling. The Broan-NuTone GLA1423BL claims “350 Max Blower CFM” and “1.5 Sones”. It ranks #184 overall and #24 in Range Hoods, comfortably the best Best Sellers Rank here. Every other hood claims at least two and a half times its airflow. Two of them, the BRANO and an unbranded hood sold under the RAPSUAR brand field, claim 1,200 CFM, more than three times the Broan figure.

An airflow number on its own is only half a claim. A fan rated at 900 or 1,200 CFM has to push that air somewhere, and in a ducted installation it pushes it through a pipe in the wall or ceiling. The narrower that pipe, the harder the fan has to work and the less air actually moves. That is why installation manuals pair a hood with a duct size, and why a high CFM figure means very little until you know the duct it expects.

Read the ten listings for a duct size and you find two. The AROAN states “6” round top, or 3‑1/4” x 10” rectangular top/back”. The BRANO says it “connects seamlessly to a 8-inch round duct”. Two more, the Tieasy and the VIKIO HOME, say they take round or rectangular ducts but give no dimensions. The Broan says top or rear venting, or non-ducted with charcoal filters sold separately, and gives no size. The other five, including the second 1,200 CFM hood, say nothing about the duct at all.

The two listings that state a duct size rank eighth and tenth of ten. The BRANO sits at #1,611 overall and the AROAN at #6,185. Shoppers are not choosing these hoods for their installation paperwork, and that is the gap this guide tries to close.

So this roundup sorts the ten by what each listing tells you about the duct behind the hood, then sets out the other things the listings do state: noise in decibels or sones, baffle or mesh filters, gesture, voice, touch or rocker controls, and the height and depth figures you need to fit a hood under a cabinet. Where a spec is missing, we say Not stated. Where two fields disagree, we report both. Star ratings and review counts were not captured for this roundup; popularity below is Amazon’s Best Sellers Rank only.

All ten were captured on 5 October 2026. Their overall Best Sellers Ranks run from #184 to #6,185, and their stated airflow from 350 to 1,200 CFM.

Our Quick Picks

At a Glance

Ten 42-Inch Hoods, Sorted by What They Say About the Duct

Read the first two columns together: every airflow claim needs a duct to match, and only the top two rows tell you which one.

#	Model	Max CFM Claimed	Duct Stated	Noise Stated	Best Sellers Rank	Standout	Main Drawback	Check Price
1	BRANO UCE16-42	1,200 CFM	8-inch round	60 dB	#303 in Range Hoods	Only 1,200 CFM claim with a named duct	9.8 in tall and 61.7 lb listed	View on Amazon
2	AROAN ARTC01-42	900 CFM	6-inch round or 3-1/4 x 10 in	65 dB max	#957 in Range Hoods	Three venting options, each with dimensions	Weakest rank on the page	View on Amazon
3	Tieasy 42-Inch Dual Motor	900 CFM	Round or rectangular, no size	60 dB max	#166 in Range Hoods	Voice, gesture, touch, remote and app control	Duct shapes named, never measured; no warranty stated	View on Amazon
4	VIKIO HOME VK-RC11-42	980 CFM	Round and rectangular adapters, no size	Not stated	#48 in Range Hoods	Third-best rank; both duct adapters included	No decibel figure; 3 speeds only	View on Amazon
5	Broan-NuTone GLA1423BL	350 CFM	Top or rear; no size	1.5 sones	#24 in Range Hoods	Best rank; ENERGY STAR; quietest stated rating	Lowest airflow; micro filters, not baffles	View on Amazon
6	JOCO JC-C01-42G	900 CFM	Not stated	40–65 dB	#113 in Range Hoods	Gesture control; 10-year motor warranty	Duct, speeds and venting options all unstated	View on Amazon
7	EKON NAC01-42	900 CFM	Not stated	65 dB max	#237 in Range Hoods	Twin motors, 4 speeds, remote and timer	Filters not called baffles; support, not warranty	View on Amazon
8	IKTCH C01-42 (unbranded title)	900 CFM	Not stated	Below 65 dB	#212 in Range Hoods	Sold by Amazon.com; gesture and touch	A bullet calls it a 30in hood	View on Amazon
9	FlyPine FNC	904 CFM (top speed)	Not stated	46–69 dB	#317 in Range Hoods	Only listing with CFM for every speed	Loudest stated top figure, 69 dB	View on Amazon
10	RAPSUAR 1200 CFM (unbranded title)	1,200 CFM	Not stated	35 dB low, under 50 dB high	#43 in Range Hoods	Second-best rank; quietest stated top speed	1,200 CFM with no duct size; 1-year warranty	View on Amazon

Best Sellers Ranks and specifications are taken from each manufacturer’s Amazon listing as displayed on 5 October 2026 through a United States connection, and may change. Airflow and noise are as each seller states them. No listing says how its CFM was measured, or at what duct size or static pressure, and none of the dB figures gives a measuring distance. The Broan’s 1.5 sones is stated “on working speed”, not at its 350 CFM maximum, and sones and decibels are not directly convertible. Two listings, the IKTCH and the RAPSUAR, carry generic titles; we name them by the brand field in each listing. The FlyPine’s 904 CFM is its stated top speed; its title says 900. Ranks are as returned on 5 October 2026; all ten are filed in Range Hoods. Two hoods, the IKTCH and the VIKIO HOME, were sold by Amazon.com at capture; the rest by their brands or third-party sellers, and seven were flagged as scarce stock. Star ratings and review counts were not captured for any product here.

Scroll the table sideways to see every column

How We Chose These Ten

We researched current listings, compared manufacturer specifications and documentation, and read each listing’s claims about airflow, ducting, noise, filters, controls and size line by line. We did not carry out hands-on testing, and nothing below is presented as measured performance data. Star ratings and review counts were not captured for this roundup. We used Amazon Best Sellers Rank, buy-box stock and listing specifications instead, and nothing on this page describes or implies how owners have scored these hoods.

• 42-inch under cabinet hoods only — every product here is sold as a 42-inch hood that mounts beneath a wall cabinet. Wall chimney hoods, island hoods and built-in inserts were not in the running.
• New units only — every buy box here was a new product at capture.
• Airflow recorded exactly as claimed — the maximum CFM figure in each listing, plus per-speed figures where a listing gives them. Only one does.
• Duct statements recorded in full — a size where one is printed, a shape where only a shape is named, a direction where only top or rear is mentioned, and Not stated where the listing is silent. We counted rather than assumed.
• Noise recorded in its own units — decibels where the listing uses decibels, sones where it uses sones, with the speed it applies to. We do not convert between the two.
• Size fields reported as listed — height, depth and width are quoted from each listing’s spec fields. Where those fields look like a box size or swap their labels, we say so. Our own arithmetic, such as duct cross-sections and air velocities, is labelled as ours.
• Implausible fields left out — where a listed weight looks wrong next to similar hoods, we do not print it.
• Popularity from Best Sellers Rank only — ranks are quoted exactly as returned on 5 October 2026, overall and in Range Hoods. Ranks move constantly.
• Verified stock and seller — each hood was the buy-box offer and in stock on amazon.com on 5 October 2026. Seven were flagged as scarce stock.

The Ten 42-Inch Under Cabinet Range Hoods in Detail

Two Duct Sizes for Ten Airflow Claims

A range hood fan is rated in cubic feet per minute, and that rating only holds when the air has somewhere to go. In a ducted installation, the duct is that somewhere. A narrow duct makes the fan work against more resistance, so less air actually moves, the motor works harder and the noise rises. That is why the duct a hood expects is the second half of its airflow claim. Here is every duct statement on the page, word for word where it matters.

The count is two of ten. Two listings give a duct size, two name shapes, one names directions, and five give nothing usable. None of the five silent listings claims less than 900 CFM, and one of them claims 1,200.

Size changes everything about a high CFM number. The table below sets each stated duct, plus two common sizes no listing names, against the airflow claims on this page. Cross-sections and velocities are our arithmetic, assuming the full claimed airflow and a smooth straight run, which real installations never quite manage. They show relative strain, not what any hood will actually move.

Read the table across, not down. Through a 6-inch round duct, 900 CFM would have to move about two and a half times faster than 350 CFM does. Through an 8-inch duct, 1,200 CFM moves more slowly than 900 CFM does through a 6-inch. Faster air means more resistance and more noise from the duct itself, so in practice a high-CFM hood on a small duct delivers well below its rating. A common installer rule of thumb pairs 6-inch ducts with hoods of a few hundred CFM, 8-inch with mid-range to around 900, and 10-inch above that. Treat that as general guidance; your hood’s installation manual is the authority.

So the BRANO’s 8-inch statement is the most useful line on the page. It is the one high-airflow claim that comes with a duct that can plausibly carry it. The AROAN’s statement is the second most useful, because it tells you honestly that a 900 CFM hood can be fitted to a 6-inch duct, and leaves you to draw the conclusion. For the five listings that say nothing, ask the seller for the collar size before you buy.

Length and bends matter too. Every elbow and every foot of duct adds resistance, and a roof cap or wall cap adds more. A 900 CFM hood on a short, straight 8-inch run to an outside wall will move far more air than the same hood on a long run with three elbows. No listing here mentions run length, and that is normal: it is a property of your kitchen, not the hood. For a sense of how this plays out at narrower widths, our 30-inch under cabinet hood roundup looks at the same duct limit on 30-inch hoods.

Noise in Two Units, and One Blank

Nine listings give noise in decibels and one in sones. They are not interchangeable. Decibels measure sound pressure on a logarithmic scale; sones measure perceived loudness on a linear one, so 2 sones sounds twice as loud as 1. Hood makers in North America often rate in sones at a set speed. None of the decibel figures here gives a distance or method, so the comparisons below are claim against claim.

The quietest claim sits on the highest airflow. The RAPSUAR says under 50 dB at 1,200 CFM. The BRANO, with the same airflow and a stated 8-inch duct, says 60 dB. Ten decibels is roughly a doubling of perceived loudness, so the two claims are far apart for hoods that claim to move the same air. Without a measuring method on either, we cannot say which is closer to what you would hear in a kitchen.

Three listings give a low-speed figure. The JOCO, FlyPine and RAPSUAR. The low figure is the one you live with most, since most cooking runs at the bottom two speeds. The FlyPine is the only one where you can pair a noise figure with an airflow figure at the same speed, roughly: 46 dB at the low end, where it moves 385 CFM.

The Broan’s 1.5 sones is the only figure in a recognised hood rating unit. It is stated on working speed, not at maximum. For a 350 CFM hood that is low, and the listing compares it to a refrigerator running. It is a different measurement from every other figure here, so read it as quiet rather than as a number to rank against 60 dB.

Noise also depends on the duct. The same hood on a 6-inch duct will usually sound louder at a given setting than on an 8-inch duct, because the air moves faster through the narrower pipe. A seller’s figure, measured under conditions they choose, is a best case. Our 36-inch range hood guide looks at how loud airflow claims get on the next size down.

Baffles, Micro Filters and the One That Will Not Say

Filters decide how much grease reaches the fan and the duct. Baffle filters are folded stainless channels that make the air change direction, so grease drops out; they cope well with high airflow and heavy frying and go in the dishwasher. Mesh or micro filters are layered screens that catch grease as the air passes through; they are lighter and common on lower-airflow hoods. Here is what each listing states.

• Baffle, stated: BRANO, AROAN (two, dual-layer), Tieasy, VIKIO HOME (two, widened), JOCO (three), IKTCH, FlyPine and RAPSUAR (two). Eight of ten.
• Micro filters: the Broan-NuTone, with “2 dishwasher-safe high efficiency micro filters” behind a fully enclosed bottom.
• Stainless, type not named: the EKON, with “3 Pcs dishwasher-safe and easy removable stainless steel permanent filters”.
• Charcoal for non-ducted use: only the Broan names one, the HPF30, sold separately.

The pattern follows airflow. The one hood with micro filters is the 350 CFM Broan; every hood that states baffles claims 900 CFM or more. All ten say their filters are dishwasher-safe. For replacement filters and what each type does, see our range hood filter guide.

Gesture, Voice, Touch or a Rocker Switch

Controls are where these hoods differ most visibly, and where the listings are most detailed.

Six of ten offer gesture control. It keeps greasy fingers off the panel, and two listings, the RAPSUAR and VIKIO HOME, say they have worked on accidental triggering. Two offer voice. Four offer a remote, though only the EKON and FlyPine put it in the core specification. The Broan’s rocker switches are the simplest controls here, and simple controls have the least to fail. If a gesture sensor sounds like a nuisance over a busy hob, the AROAN, EKON and FlyPine are the touch-only options.

Height, Depth and the Fit Under Your Cabinet

A 42-inch under cabinet hood has to fit three ways: the width of the cabinet run, the gap between cooktop and cabinet, and the depth of the cabinet above. Here are the listed size fields.

Seven hoods sit between 5.9 and 7.0 inches tall. Most of the field shares a roughly 6 by 19.7 inch profile, which suggests a common chassis behind several brands. The BRANO is the outlier you can trust: 9.8 inches tall and 22.0 inches deep, giving deeper front-burner coverage at the cost of headroom. The IKTCH and VIKIO HOME fields do not describe a hood of the usual shape, and both are worth confirming. If headroom is tight, our low profile under cabinet hood roundup covers slimmer designs, and if you would rather hide the hood inside the cabinetry altogether, see our hidden range hood guide.

Width is rarely exactly 42. Most list 41.5 to 41.75 inches, which leaves a little play inside a 42-inch cabinet opening. Only the Broan and RAPSUAR give 42.0 exactly.

Why 42 Inches Over a 36-Inch Range

As general guidance, a hood should be at least as wide as the cooktop below it, and a little wider is better. Smoke and steam rise in a plume that spreads as it climbs, and the outer edges of a wide range sit closest to the hood’s edges. A 42-inch hood over a 36-inch range gives three inches of overhang on each side, by our arithmetic, which helps catch what drifts off the outer burners. A 42-inch hood can also sit over a 30-inch range, with six inches each side, if the cabinet opening is 42 inches. Over a 42-inch or wider range, a 42-inch hood is the minimum, not the ideal.

How much airflow a 36-inch range needs depends on the range. One common rule of thumb for wall-mounted hoods is about 100 CFM per linear foot of cooktop, which puts a 36-inch range at about 300 CFM, close to the Broan’s 350. Another, for gas ranges, works from total burner output: roughly 100 CFM for every 10,000 BTU. A powerful 36-inch gas range can push that figure well past 600. Both are general guides, not rules, and both assume the hood’s air can actually leave through the duct. If you are still choosing the range itself, our 36-inch range hood guide covers hoods built for that width.

Installation: Wiring, Make-Up Air and Who Should Fit It

Electrics first. Only one listing says how its hood is powered: the FlyPine runs from “a standard 120V/60Hz 3-prong plug” or can be hardwired by a professional. The rest say nothing. If there is no outlet in the cabinet above, or the hood must be hardwired, that generally means an electrician, and in many areas permanent wiring work must be done or signed off by a licensed one. The Broan names an optional HAWSK3 low-voltage wall switch kit for ADA installations.

Make-up air is the issue high-CFM buyers miss. A hood that pushes several hundred cubic feet of air out of the house every minute has to draw the same amount back in from somewhere. In a tight modern house, that can mean air pulled down a chimney or flue, which matters where there are fuel-burning appliances, such as a gas water heater, furnace or fireplace, because it can draw combustion gases, including carbon monoxide, back into the living space. Some areas require make-up air systems for kitchen exhausts above a set airflow; the threshold and the rules vary, so check with your local building department before installing a 900 or 1,200 CFM hood. Only the Broan mentions make-up air, naming optional MD6TU, MD8TU and MD10TU dampers, and it is the hood that needs it least.

Weight and mounting. Listed weights run from 24.25 pounds on the Broan to 61.7 on the BRANO. The heavier hoods need solid fixing into the cabinet base and a second pair of hands. The Broan claims one-person installation with its EZ1 brackets.

A backdraft damper keeps outside air out. Only the VIKIO HOME describes one, on its rectangular adapter; its round adapter has none. Ask whether the others include one.

Popularity Runs Opposite to Paperwork

Star ratings were not captured for this roundup, so the only popularity measure is Amazon’s Best Sellers Rank, as returned on 5 October 2026. All ten are filed in Range Hoods, so the category ranks compare directly. Ranks move constantly; read the order, not the precise numbers.

The best seller claims the least airflow, and the two duct statements rank eighth and tenth. The Broan’s lead may come from brand recognition, its sones rating, its ENERGY STAR label or simple familiarity; the rank cannot tell us which. What the table does show is that shoppers are not rewarding the listings that document installation. That is a reason to ask the questions yourself.

Best Alternatives

What the Step Up Buys

The everyday tier — Broan-NuTone. 350 CFM, 1.5 sones on working speed, micro filters, rocker switches, ENERGY STAR, a non-ducted option and the best rank on the page. It asks the least of your duct and your electrician. What it does not do is clear heavy smoke from high-heat searing on a powerful gas range.

The 900 CFM tier — AROAN, JOCO, EKON, IKTCH, Tieasy, FlyPine, VIKIO HOME. Stepping up buys roughly two and a half times the claimed airflow, stainless baffle filters on all but the EKON, which does not say, four speeds on most, and gesture, remote or app control depending on the listing. It also buys a duct question that only the AROAN answers fully. Within the tier, the choice is between documentation (AROAN, FlyPine), warranty (JOCO, FlyPine, AROAN), controls (Tieasy) and rank (VIKIO HOME, JOCO).

The 1,200 CFM tier — BRANO, RAPSUAR. The top step buys a third more claimed airflow than the 900 group. The BRANO adds an 8-inch duct statement, six speeds, voice control and a 5-year warranty, at the cost of height and weight. The RAPSUAR adds the quietest noise claim and a strong rank, with no duct statement and a 1-year warranty. At this airflow, make-up air questions become more likely in some areas, and a 6-inch duct becomes a serious bottleneck.

Higher price does not track documentation. The lowest-priced group includes the AROAN, the best-documented 900 CFM hood; the premium end includes both the BRANO, the best-documented 1,200 CFM hood, and the FlyPine, which documents speeds but not the duct. Pay for the information you need, not the number in the title.

What to Check Before You Buy

Measure Your Existing Duct

If you are replacing a hood, take the old one down or look in the cabinet above and measure the duct: round diameter, or rectangular width and height. On this page, only the AROAN and BRANO tell you what they connect to. For the other eight, send the seller your measurement and ask whether the collar matches without an adapter.

Match the CFM Claim to the Duct

A 900 or 1,200 CFM hood on a 6-inch duct will move far less than its rating, by the arithmetic above. If you want the airflow you are paying for, plan an 8-inch or larger duct for the high-airflow hoods, as the BRANO’s listing does. If you are keeping a 6-inch duct, a lower-airflow hood, or one whose lower speeds are documented like the FlyPine, makes more sense.

Check the Mounting Height and Hood Height

Most hoods here are about 6 inches tall; the BRANO is 9.8. Measure from cooktop to cabinet base and check the hood maker’s recommended mounting height in the manual. A taller hood takes headroom; a hood mounted too high captures less smoke.

Ask How the Noise Was Measured

Claims run from 35 dB low on the RAPSUAR to 69 dB high on the FlyPine, plus 1.5 sones on the Broan and nothing on the VIKIO HOME. None states a distance or method. Ask, and prefer listings that give both a low and a high figure.

Confirm the Filter Type

Eight say baffle. The Broan says micro filters, which suits its lower airflow. The EKON says stainless permanent filters without naming a type. If you fry or sear often, baffles are the usual choice for high airflow.

Plan the Wiring

Only the FlyPine states plug-in or hardwired. Find out which your hood needs, and whether there is an outlet in the cabinet. Hardwiring generally means an electrician.

Check Local Make-Up Air Rules

High-airflow hoods can trigger make-up air requirements in some areas, especially in tight houses with fuel-burning appliances. Ask your local building department before you install a 900 or 1,200 CFM hood, and budget for a make-up air damper if one is needed.

Common Mistakes

• Reading the CFM figure without the duct. Eight of ten listings give no duct size; 900 CFM through a 6-inch round would move at about 4,580 ft/min, by our arithmetic.
• Assuming 1,200 CFM always beats 900. On a 6-inch duct, neither will get near its rating; only the BRANO pairs 1,200 CFM with an 8-inch duct.
• Comparing sones with decibels. The Broan’s 1.5 sones and the JOCO’s 65 dB are different measures and cannot be ranked directly.
• Trusting a noise claim without a method. The RAPSUAR claims under 50 dB at 1,200 CFM; the BRANO claims 60 dB at the same airflow.
• Ignoring the hood’s height. The BRANO is 9.8 inches tall against about 6 inches for most; that is nearly four inches of headroom.
• Taking the size fields on trust. The IKTCH’s fields never show 42 inches and a bullet calls it 30in; the VIKIO HOME lists 18.5 in height.
• Forgetting make-up air. A 900 CFM hood exhausts 900 cubic feet a minute at its rating; in a tight house with a gas appliance, that air has to come back in safely.
• Buying by rank alone. The best-ranked hood claims 350 CFM; the two listings that state a duct size rank eighth and tenth.

Who Should Buy Which

Buy the BRANO if you cook hard over a 36-inch range and can run an 8-inch duct. It is the only 1,200 CFM claim with a named duct, with six speeds, voice, gesture and touch control and a 5-year warranty. Accept 9.8 inches of height and 61.7 pounds.

Buy the AROAN if you are replacing a hood on an existing duct. It tells you it fits a 6-inch round or a 3-1/4 x 10 inch rectangular duct, with a 10-year motor warranty and a slim 6.0-inch profile. Accept that 900 CFM will not be fully delivered on a 6-inch duct, and the weakest rank here.

Buy the Tieasy if you want to run your hood by voice or phone. Alexa, Google Assistant, an app, gesture, touch and a remote, with a 60 dB stated maximum. Get the duct collar size and the warranty terms from the seller first.

Buy the VIKIO HOME if you want a well-ranked high-CFM hood with both adapters in the box. 980 CFM claimed, GU10 bulbs and sold by Amazon.com. Confirm the adapter sizes, the noise level and the installed height before ordering.

Buy the Broan-NuTone if your cooking is everyday and your duct is modest, or missing. 350 CFM at 1.5 sones, ENERGY STAR, a non-ducted option and the best rank on the page. Accept micro filters, two speeds and a 1-year base warranty.

Buy the JOCO if you value a long motor warranty and quiet low speeds. 40 dB low, three baffles, gesture control and 10 years on the motor. Ask for the duct size and speed count.

Buy the EKON if you want a remote and timer without gestures. Twin motors, four speeds and a touch screen. Confirm the filter type and what its technical support terms cover.

Buy the IKTCH if you want Amazon.com as the seller. A conventional gesture-and-touch 900 CFM hood with a 2-year warranty. Confirm it is 42 inches wide before you order.

Buy the FlyPine if you want to know what each speed delivers. 385, 490, 715 and 904 CFM stated, plug-in or hardwired, ETL listed, 10 years on the motor. Accept the highest stated top-speed noise, 69 dB.

Buy the RAPSUAR only after the seller confirms the duct and the noise method. The boldest numbers here, 1,200 CFM and under 50 dB, and a strong rank, with no duct statement and a 1-year warranty.

Frequently Asked Questions

Final Verdict

Nine of these ten hoods claim 900 CFM or more, and eight of the ten never tell you the duct that airflow needs. The AROAN states a 6-inch round or 3-1/4 by 10 inch rectangular duct. The BRANO states an 8-inch round. Everyone else names a shape, a direction or nothing at all, including the other 1,200 CFM hood. Yet duct size decides how much of a CFM claim you actually get: by our arithmetic, 900 CFM through a 6-inch round would move nearly 78% faster than through an 8-inch.

The market is not rewarding the paperwork. The best-selling hood claims 350 CFM. The two listings that state duct sizes rank eighth and tenth. The quietest noise claim, under 50 dB, sits on a 1,200 CFM hood that says nothing about installation, and no decibel figure on the page comes with a method.

So buy a 42-inch hood by its duct first and its CFM second. Measure what is in your wall, or decide what you can run. Then pick airflow that duct can carry, check the hood’s height against your cabinet, confirm baffles if you fry, and find out whether it plugs in or must be hardwired. For a 900 or 1,200 CFM hood, ask your local building department about make-up air before you install.

If you buy one hood from this page, make it the BRANO: the only 1,200 CFM claim backed by a stated 8-inch duct, with six speeds and a 5-year warranty. If you are keeping an existing 6-inch or 3-1/4 by 10 inch duct, the AROAN is the one listing that confirms the fit, and if your cooking is everyday, the Broan-NuTone does the job at 350 CFM and 1.5 sones.