What Size Range Hood Do I Need? CFM Calculator & Buying Guide
Size the hood around your cooking surface, installation location, cooking output, capture area, and duct system—then identify the type of range hood worth comparing next.
A range hood has two jobs that shoppers often combine into one number: capture the plume rising from the pans, and move the captured air through the ventilation path. Width and canopy depth influence capture. CFM describes air volume. Duct resistance influences how much of the rated airflow survives the real installation. A powerful blower under a narrow canopy or behind an undersized duct can still perform poorly.
Larmine Range Hood CFM Calculator
This calculator compares published methods instead of hiding them inside a proprietary score. It uses HVI width-based guidance and, when gas is selected, shows the Broan-NuTone high-output gas check of 1 CFM per 100 BTU. The planning target is the higher applicable recommendation.
Your planning result
This is a planning estimate, not code approval or a substitute for the selected hood and cooking-appliance instructions. Local adoption and amendments vary. A qualified HVAC professional should review high-CFM systems, complex ducts, combustion-safety concerns, and makeup-air design.
How range hood sizing works
A useful selection sequence is: identify the cooking appliance; confirm its width and maximum output; determine whether the hood will be against a wall or over an island; choose a canopy that can capture the plume; calculate a starting airflow; then check whether the proposed duct and makeup-air plan can support that airflow. The hood and cooking-appliance manufacturers have the final product-specific requirements.
The calculator deliberately does not multiply CFM for every elbow or heavy-cooking habit. Published product manuals convert each fitting into equivalent duct length differently, and blower curves respond differently to static pressure. Adding an unsupported percentage would look precise but could be wrong. Instead, the calculator flags restrictive paths for manufacturer-specific duct review.
Range hood width versus cooktop width
For a wall installation, begin with a hood that matches or exceeds the cooking-surface width. Broan-NuTone and Zephyr present matching width as a basic starting point, while Wolf notes that a wider hood can improve capture where space permits. A 30-inch range therefore usually starts the search among 30-inch or wider compatible hoods; a 36-inch cooktop starts among 36-inch or wider models.
Once you know a standard 30-inch hood fits your opening and airflow plan, compare Larmine’s best 30-inch range hoods for different kitchens.
Island installations are exposed to cross-drafts and lack the back wall that helps contain the plume. Wolf specifies that its island hoods should extend at least 3 inches beyond the cooking surface on each side. That is useful manufacturer guidance, not a universal U.S. rule. Confirm the selected hood and cooking appliance as a pair before cutting cabinets or ordering a decorative surround.
How much CFM do you need?
CFM means cubic feet per minute: the volume of air the hood is rated to move in one minute under a stated test condition. HVI recommends 100 CFM per linear foot of range for wall hoods and 150 CFM per linear foot for island hoods. HVI also publishes lower minimum reference rates of 40 and 50 CFM per linear foot, respectively. For a 30-inch wall installation, the HVI table shows 250 CFM recommended and 100 CFM minimum; for a 36-inch wall installation, 300 CFM recommended and 120 CFM minimum.
Those figures are ventilation guidance—not a guarantee that a particular canopy will capture every plume, and not a substitute for local code. Cooking style, appliance output, hood depth, mounting height, and installed duct resistance remain important.
| Installation | HVI minimum reference | HVI recommended rate | 30-inch example | 36-inch example |
|---|---|---|---|---|
| Against a wall | 40 CFM per linear foot | 100 CFM per linear foot | 100 minimum / 250 recommended | 120 minimum / 300 recommended |
| Island | 50 CFM per linear foot | 150 CFM per linear foot | 125 minimum / 375 recommended | 150 minimum / 450 recommended |
Electric and induction cooktops
For conventional electric and induction cooking, the HVI width-and-location method offers a transparent starting point. Induction can reduce waste heat at the cooking surface, but boiling, frying, searing, and oil aerosols still create moisture and particles that need capture. Do not select a hood only because the appliance is electric.
For a typical 30-inch wall installation, the HVI minimum reference is 100 CFM and the HVI recommended airflow is 250 CFM. For a 36-inch wall installation, the HVI minimum reference is 120 CFM and the HVI recommended airflow is 300 CFM. These are planning references. A larger canopy, intense cooking, a high mounting position, or a restrictive duct path can move the product decision upward, subject to the manufacturer’s documented options.
Gas ranges and BTU output
Gas adds a second sizing check because the appliance’s total maximum input can vary widely even at the same width. Broan-NuTone recommends at least 1 CFM per 100 BTU for high-output gas ranges or cooktops. The calculator divides the appliance’s documented total BTU/hr by 100 and compares that result with the HVI width recommendation. It uses the higher number as the planning target.
Example: a 30-inch wall range rated at 50,000 BTU/hr produces a 500 CFM BTU check, which is higher than HVI’s 250 CFM width recommendation. The output therefore highlights 500 CFM as the planning target. This is a conservative synthesis of two published recommendations—not code and not a universal manufacturer rule. A pro-style appliance manual may require a specific hood, width, blower, or mounting range.
Wall-mounted versus island hoods
HVI’s recommended rate rises from 100 CFM per linear foot at a wall to 150 CFM per linear foot at an island. The higher island rate reflects the more exposed capture environment. Air movement from people, HVAC registers, doors, and open rooms can push the cooking plume sideways before the hood captures it.
Width also matters more over an island. A deeper and wider canopy can intercept a drifting plume without relying only on blower speed. Raising an island hood higher than the manufacturer’s recommended position can reduce capture; do not compensate casually with a bigger motor.
Why capture area matters
Smoke that never enters the hood cannot be rescued by a rating on the box. Canopy width, depth, shape, and mounting height determine the capture zone. A hood the same width as the cooktop may work well when mounted within its documented range and used for moderate cooking, yet allow edge plumes to escape when shallow, high, or exposed to cross-drafts.
Cabinet constraints are part of sizing. An under-cabinet hood must fit the opening and preserve required clearances. An insert must be approved for the custom enclosure and paired with a compatible liner where required. Confirm cabinet depth, blower location, electrical access, filter removal space, and the duct transition before ordering.
Ducted versus ductless range hoods
A ducted hood captures air and discharges it outdoors through a wall or roof termination. It can remove cooking particles, odors, moisture, and heat from the home when properly designed. HVI states that nonducted recirculating hoods provide no actual ventilation, and recommends direct outdoor exhaust for optimum kitchen air quality.
A ductless or recirculating hood pulls air through grease and often charcoal filters, then returns it to the kitchen. It may reduce some grease and odor when the correct filters are maintained, but it does not remove moisture and heat outdoors in the same way. Whirlpool and Broan describe recirculation as a distinct configuration, not an equivalent exhaust path. Verify filter availability, replacement intervals, and whether the selected model is listed for conversion.
For a room-by-room decision framework, compare ducted and ductless range hoods by cooking pollutants, moisture, installation constraints, noise, and filter maintenance.
Duct diameter, length, and elbows
Why duct diameter matters
The hood outlet and installation manual determine the approved duct size. Broan advises against reducing existing duct below the hood specification and notes that higher-output hoods can require larger ducts. An undersized duct increases resistance, lowers delivered airflow, and can increase noise. Do not connect a range hood to dryer duct or plastic duct.
Before choosing a hood, use the range hood duct size guide to compare common 6-, 8-, and 10-inch configurations and verify the existing route.
Why straight, smooth metal duct helps
Broan prefers smooth metal over flexible metal because corrugations create turbulence. Faber likewise documents short, straight routing, uniform duct size, separated elbows, and all-metal ductwork for specific models. These are consistent design principles; exact equivalent-length limits and fitting penalties remain product-specific.
Duct length and elbows
Every turn consumes part of the blower’s pressure capability. A roof cap, wall cap, transition, backdraft damper, and dirty filter can add resistance too. Use the selected manufacturer’s equivalent-length table or blower curve rather than a universal maximum. The shortest practical exterior route with few turns often performs best.
Why advertised CFM is not the whole story
Maximum blower airflow may be measured under conditions that do not resemble the finished duct. Broan explains that installed performance depends on duct length, diameter, bends, static pressure, and termination. HVI-certified ratings provide a standardized basis for comparing airflow and sound, but the installed system still has to preserve that performance.
Compare the rating point, not just the largest number in marketing copy. Look for HVI-certified airflow where available, the specified duct size, supported blower configuration, and published sound at a stated speed or airflow. A useful hood is one the household will actually operate.
Makeup air considerations
Exhausting air changes pressure inside the home. In a tight house, a high-capacity hood can pull air through leaks or interact with fireplaces, naturally drafted water heaters, furnaces, and other combustion appliances. Makeup air is a designed replacement-air path—not simply an open window assumption.
The 2024 International Residential Code Section M1503.6 requires makeup air under its stated conditions when an exhaust system is capable of more than 400 CFM and certain non-direct-vent or non-mechanically drafted fuel-burning appliances are inside the dwelling’s air barrier. The section calls for replacement airflow approximately equal to exhaust airflow and specifies damper provisions. Earlier editions and local amendments can differ materially.
Noise and sones
A sone is a linear loudness unit: HVI explains that doubling the sone value sounds roughly twice as loud. Sound must be compared at equivalent operating conditions. A quiet claim at low speed is not directly comparable with another hood’s rating at high speed.
High maximum CFM can bring more fan and air noise, especially through a restrictive duct. Multiple speeds are useful because light cooking can run quietly while searing or frying can use a higher setting. Check HVI-certified sound information where available, the airflow associated with the rating, and reviews of control usability later in the buying process.
Common range hood sizes
What size range hood for a 30-inch stove?
Start with a 30-inch or wider wall hood that the cooking-appliance manual permits. HVI’s wall-width method gives 250 CFM recommended and 100 CFM minimum reference. If the stove is gas, compare that with total BTU divided by 100 when applying Broan’s high-output guidance. An island application changes the HVI recommendation to 375 CFM and may benefit from a wider canopy.
What size range hood for a 36-inch stove?
Start with a 36-inch or wider compatible wall hood. HVI gives 300 CFM recommended and 120 CFM minimum reference for a 36-inch wall installation. Over an island, the recommended value becomes 450 CFM. High-output gas appliances can exceed both width-based figures.
Larger and pro-style ranges
HVI directs readers to the cooktop manufacturer’s advice for professional-style equipment. Wolf’s own ventilation guide illustrates why: recommended blower values change by appliance model, cooking modules, griddle or charbroiler configuration, hood type, and duct length. Do not size a 48- or 60-inch pro-style range by width alone.
Common sizing mistakes
- Choosing the same width but ignoring capture depth: edge plumes can escape a shallow hood.
- Mounting too high: the plume spreads before it reaches the canopy.
- Reducing the duct: a powerful blower cannot overcome every restriction quietly.
- Using a long route with many elbows: delivered airflow can be much lower than the advertised maximum.
- Treating recirculation as outdoor exhaust: moisture and heat remain in the room.
- Buying high CFM before planning makeup air: the ventilation decision can affect HVAC and combustion safety.
- Ignoring sound: a loud hood that stays off provides no capture.
- Ordering before checking cabinets: the insert, liner, duct transition, and filter access may not fit.
- Using wall assumptions at an island: exposed plumes need more capture consideration.
- Ignoring gas output: equal-width gas appliances can have very different BTU totals.
Range hood buying guide
Once width and airflow are narrowed, choose the installation family. This article intentionally stops before product rankings; the next step is comparing products within the right category using verified specifications.
Under-cabinet hood
Useful when upper cabinets remain. Check cabinet depth, discharge direction, duct transition, lighting, and filter removal.
Wall-mount chimney hood
Works as a visible focal point without an upper cabinet. Confirm ceiling height, chimney coverage, mounting range, and exterior path.
Insert and liner
Fits a custom decorative enclosure. The insert, liner, blower, enclosure dimensions, and clearances must be compatible.
Island hood
Needs ceiling support, electrical and duct routing, sufficient capture area, and attention to cross-currents.
Ductless or convertible
Consider only with realistic expectations and confirmed charcoal-filter availability. It does not exhaust moisture outdoors.
High-CFM gas hood
Coordinate appliance output, hood system, larger duct, makeup air, noise, and professional installation before purchase.
300 versus 400 CFM
For a 36-inch wall cooktop, HVI’s width recommendation is 300 CFM. A 400 CFM hood may provide additional capacity, but the better choice depends on capture geometry, cooking output, rating method, sound, and duct design. Crossing 400 CFM is also not the same as exceeding it under the 2024 IRC wording, and local adoption still governs.
When 600 CFM enters the conversation
Six hundred CFM may be relevant for a high-output gas appliance, some island or pro-style installations, or a manufacturer-specified system. It may also require a larger duct and makeup-air review. Do not buy 600 CFM merely because it appears safer than 300 CFM.
Future product-shopping framework
For each candidate, record: exact width and depth; approved mounting height; HVI-certified airflow if available; CFM at the relevant setting; sone rating at a stated speed; required duct diameter; permitted discharge directions; equivalent-length limit; filter type and replacement cost; lighting; controls; warranty; required liner, blower, damper, or recirculation kit; and whether makeup air has been resolved.
A comparison table should place like against like. A 300 CFM under-cabinet hood is not a direct substitute for a 600 CFM remote-blower insert simply because both are 30 inches wide.
Installation considerations
Before purchase, trace a complete route from hood outlet to exterior termination and confirm that the required duct can fit without cutting prohibited structural members. Verify hood-to-cooking-surface height, cabinet combustibility clearances, electrical supply, ceiling support for island units, and access for service and filter removal.
Professional help is appropriate for new wall or roof penetrations, electrical circuit changes, gas-appliance changes, difficult duct routing, high-CFM systems, makeup-air design, structural or cabinet modifications, and uncertainty about permits or adopted code. The article does not provide gas, electrical, structural, or roof-flashing instructions.
DIY versus professional installation
Replacing a compatible hood on an existing approved duct and electrical connection may be within the skills of an experienced homeowner who follows both manuals and local requirements. A new exhaust path is different: hidden utilities, fire-safe duct construction, weatherproof termination, roof work, electrical connections, combustion safety, and structural support can overlap. Stop and involve qualified trades when the scope moves beyond a like-for-like appliance replacement.
Frequently asked questions
How many CFM should a range hood have?
Use width, wall versus island location, cooking output, capture geometry, and manufacturer instructions. HVI recommends 100 CFM per linear foot at a wall and 150 CFM per linear foot at an island; high-output gas may require a separate BTU check.
Is a 300 CFM hood enough for a 30-inch gas stove?
Not necessarily. HVI’s 30-inch wall width recommendation is 250 CFM, but Broan’s high-output gas method may produce a higher value. Use the appliance’s documented total BTU and both manufacturers’ instructions.
Do I need a 36-inch hood over a 30-inch range?
A wall hood at least as wide as the range is a common starting point, and a wider hood can improve capture where the manuals and cabinets allow it. Island installations often benefit from greater overhang; Wolf specifies 3 inches on each side for its island guidance.
Is 600 CFM too much?
It can be appropriate for some high-output or exposed installations, but it can also require larger ductwork, makeup-air review, more installation planning, and careful sound comparison. More CFM is not automatically better.
Does an induction cooktop need a range hood?
Induction avoids combustion at the burner, but cooking still produces moisture, grease aerosols, particles, odors, and heat. Size capture and airflow around the cooking activity and installation.
Can a ductless hood remove cooking moisture?
It returns filtered air to the kitchen rather than exhausting it outdoors, so it does not remove moisture and heat in the same way as a ducted hood.
What duct size do I need?
Use the exact hood installation instructions. Do not reduce the duct below the specified outlet size. Higher-CFM systems commonly require larger ducts, but there is no universal diameter for every hood.
Does every hood over 400 CFM require makeup air?
No universal statement is accurate. The 2024 IRC language applies above 400 CFM under stated combustion-appliance conditions, while local adoption and amendments vary. Ask the local authority and a qualified HVAC professional.
Printable range hood pre-purchase checklist
- □ Cooking appliance model and installation manual saved.
- □ Cooktop/range width measured.
- □ Maximum total gas BTU documented, if applicable.
- □ Wall, island, peninsula, under-cabinet, or insert location defined.
- □ Hood width and depth provide an appropriate capture area.
- □ Manufacturer mounting-height range confirmed.
- □ HVI width-based airflow reference calculated.
- □ Gas BTU method compared when applicable.
- □ Product-specific hood requirement checked in the cooking-appliance manual.
- □ Exterior termination location identified for a ducted system.
- □ Required duct diameter fits the proposed route.
- □ Straight length, elbows, transitions, and cap counted.
- □ Manufacturer equivalent-length limit checked.
- □ Smooth metal duct and required fire-safe materials specified.
- □ Cabinet, liner, chimney, and filter-service clearances checked.
- □ HVI-certified airflow and sound ratings compared where available.
- □ Makeup-air and combustion-safety review completed if applicable.
- □ Adopted local code, permits, and amendments confirmed.
- □ Electrical, structural, roof, and HVAC professionals scheduled where needed.
- □ No product ordered until hood, appliance, duct, and cabinet requirements agree.
Project: ____________________ Appliance: ____________________ Width: ______ in. Gas input: ______ BTU/hr Proposed hood: ____________________
Conclusion
The right range hood is a coordinated capture-and-airflow system. Start with cooking-surface width, increase attention to capture at an island, compare HVI guidance with gas-output guidance when applicable, and make sure the duct can deliver the promised airflow. Resolve noise, makeup air, cabinets, and installation access before choosing a product category.
Continue planning through the Larmine Kitchen hub. For projects that involve new ducts, exterior penetrations, electrical work, or broader renovation coordination, visit the Home Improvement hub.
Sources and methodology
This guide uses current U.S. primary sources and manufacturer documents accessed August 9, 2026. The calculator presents HVI recommendations, Broan-NuTone gas guidance, manufacturer-specific width concepts, and a clearly labeled Larmine synthesis. It is not an installation design, product endorsement, or code determination.
- Home Ventilating Institute: How Much Ventilation Do I Need? — wall/island recommended and minimum rates, island multiplier, pro-style boundary, ducted preference.
- HVI FAQs — sones and certified-performance context.
- Broan-NuTone: Airflow 101 — CFM, 1 CFM per 100 BTU example, installed resistance, HVI testing.
- Broan-NuTone Support: range/cooktop CFM — high-output gas guidance.
- Broan-NuTone Support: range-hood duct — metal duct, smooth versus flexible, no reduction below specification.
- Zephyr Product Education — capture area, width, mounting height, and kitchen-volume method context.
- Wolf Ventilation Guide — wall and island width, capture area, CFM, mounting height, and appliance-specific selection.
- Faber Inca Smart installation instructions — uniform short duct, elbow limits as model guidance, metal duct, flexible-duct warning.
- Whirlpool: Ducted versus ductless range hoods — exhaust versus recirculating operation and filter context.
- 2024 International Residential Code, Chapter 15 — M1503.5, M1503.6, and Table M1505.5; local adoption and amendments must be verified.
Editorial boundaries: Larmine did not physically test, rank, price, sponsor, or endorse any range hood in this guide. No affiliate links are present. All diagrams are original simplified educational illustrations, not manufacturer-approved drawings.