What Size Range Hood Do I Need? CFM for Gas, Electric and Induction Cooktops

Choosing a range hood looks simple until the product page starts throwing CFM, BTU, duct sizes, sones and mounting heights at you. A 30-inch cooktop may be paired with a 300 CFM hood in one kitchen and a 600 CFM model in another, and both recommendations can make sense because they are solving different cooking and installation problems.

The practical way to size a hood is to begin with the cooking surface and its location, then check gas output when relevant, and finally make sure the hood can actually capture and move that air through the planned duct. This guide walks through that sequence for gas, conventional electric and induction cooktops without treating one rule of thumb as a universal law.

Range Hood CFM by Cooktop Size: A Fast Starting Table

These figures are planning baselines, not shopping instructions. A 36 in electric cooktop against a wall may be well served by a properly designed 300 CFM hood, while a 36 in professional-style gas range with 60,000 BTU/h of total burner input can push the airflow check much higher. An island installation also needs more help because there is no wall behind the plume to contain it.

What CFM Actually Tells You — and What It Does Not

Airflow only helps after the hood captures the plume

The hot cooking plume naturally rises, but front burners and tall pans can push it beyond a shallow hood.

A deeper or slightly wider hood can improve capture without relying only on a larger blower.

Island hoods work in open air and are more exposed to cross-drafts, so they usually need more capture area and airflow.

Installing a hood higher than its approved range can reduce capture even when the blower rating stays the same.

1. Start With Cooktop Width and Hood Location

For a straightforward residential starting point, the Home Ventilating Institute recommends about 100 CFM per linear foot of cooking surface for a hood against a wall and about 150 CFM per linear foot for an island hood. Convert the cooktop width to feet, multiply by the appropriate rate and then compare the result with the actual hood models available.

Wall hood planning airflow:
CFM ≈ cooktop width in feet × 100

Island hood planning airflow:
CFM ≈ cooktop width in feet × 150

Metric conversion:
m³/h ≈ CFM × 1.699

2. For Gas, Check the Total Burner BTU as Well

Gas cooking adds another useful sizing check because high-output burners can create a stronger thermal plume and combustion products as well as the smoke, grease and water vapour produced by cooking itself. A widely used manufacturer guideline for high-output gas equipment is approximately 1 CFM of exhaust for every 100 BTU/h of total burner input.

Gas-output planning check:
CFM ≈ total burner BTU/h ÷ 100

Example:
60,000 BTU/h ÷ 100 = 600 CFM

3. Electric and Induction Still Need Real Ventilation

Electric resistance and induction cooktops do not create the same combustion products as a gas flame, so their ventilation problem is generally simpler. They still produce cooking-generated particles, grease aerosols, odours, moisture and smoke. Frying bacon on induction does not become an indoor-air-quality hobby just because there is no flame under the pan.

4. Hood Width Can Matter as Much as Fan Power

A hood should generally be at least as wide as the cooking surface unless the specific product instructions say otherwise. More capture area can be especially useful over islands, front-heavy cooking layouts and high-heat appliances. A wider hood gives the rising plume more room to enter the hood before room air carries it away.

A wider capture area catches what extra CFM cannot chase later

At minimum, match the hood to the cooking surface unless the product instructions specify another arrangement.

A few extra inches of overhang can help catch a plume that spreads beyond the pan, particularly in an island layout.

Width does not excuse poor depth: front burners can still sit outside a shallow capture zone.

Confirm adjacent cabinet clearances and the approved hood size before finalising the kitchen design.

5. Mounting Height Changes Capture

Every hood has an approved or recommended mounting-height range. Install it too low and you can create clearance, heat or usability problems. Install it too high and the cooking plume has more time to spread before it reaches the hood. A larger blower does not automatically repair a hood that is positioned outside the manufacturer's intended geometry.

6. The Duct Can Turn a Strong Hood Into a Weak One

A range hood does not deliver its showroom airflow through any duct you happen to have. Long runs, undersized ducts, sharp elbows, restrictive transitions and poor terminations increase resistance. Manufacturers repeatedly recommend short, straight duct runs and the specified duct size because the fan has to work against the entire path to outdoors.

• Use the duct size specified for the exact hood or blower; do not reduce it simply to fit an old opening.
• Prefer smooth metal ductwork where required or recommended for the range hood system.
• Keep the route short and direct, with as few turns and transitions as practical.
• Use a proper exterior wall or roof cap and keep its damper free to operate.
• Seal joints as instructed so greasy exhaust does not leak into cabinets, ceilings or wall cavities.
• Check the manufacturer's equivalent-length or maximum-duct guidance instead of inventing a fixed CFM penalty for every elbow.

Two 600 CFM hoods can perform very differently after the duct is connected

A short, correctly sized route lets the blower operate closer to its intended performance.

Each elbow and transition adds resistance, especially when the duct is already too small.

Do not reduce an 8 in outlet to a convenient old 6 in duct unless the manufacturer explicitly permits that configuration.

Plan the duct before ordering cabinets; the shortest path to outdoors is easier to draw before the kitchen is built.

Rated CFM Is Not Always Delivered CFM

The number printed on a product page may describe a maximum blower rating, a certified airflow at a test condition or another manufacturer figure. Installed airflow can be lower once the real duct system adds static pressure. When comparing serious candidates, look beyond the largest number in the marketing headline.

Ducted vs Recirculating: They Solve Different Problems

A ducted hood sends captured air outdoors. A recirculating or ductless hood passes air through grease and usually odour filters before returning it to the kitchen. Recirculation can be useful where exterior ducting is impossible, but it is not equivalent to exhausting moisture, heat and combustion products outdoors.

Make-Up Air: Why Very Large Exhaust Fans Need More Planning

A powerful hood removes a large amount of indoor air. That air has to be replaced from somewhere. In a leaky older house it may arrive unintentionally through cracks; in a tighter home the pressure difference can become much more significant. The concern is not only comfort. Depressurisation can interact with fireplaces and naturally drafted fuel-burning appliances, so make-up air belongs in the design conversation before a high-CFM hood is purchased.

Every cubic foot exhausted has to be replaced somehow

The hood pushes indoor air outdoors and lowers pressure unless replacement air can enter.

A planned make-up-air path is different from hoping air leaks through random gaps.

Fuel-burning appliances and fireplaces can make pressure balance a safety issue, not only an energy issue.

The correct make-up-air strategy depends on the adopted code, climate, appliance venting and total exhaust system.

Cooking Style Can Matter More Than the Fuel Label

Someone simmering soup twice a week and someone searing steaks on cast iron every evening do not create the same plume. If you regularly fry, wok-cook, griddle, blacken, boil large pots or use multiple burners at high output, give more weight to capture area, higher usable fan speeds and a duct system that can support them.

Does Kitchen Volume Matter? Use It as a Cross-Check, Not the Main Hood Rule

You will sometimes see range hoods sized from kitchen volume and air changes per hour. Room-volume ventilation can be useful as a secondary check, especially when comparing general kitchen exhaust. But an overhead range hood is a source-capture device: catching the plume above the cooktop is usually more important than exchanging the entire room volume a chosen number of times.

Room-volume cross-check:
CFM = kitchen volume in ft³ × desired air changes per hour ÷ 60

Example only:
12 ft × 15 ft × 9 ft = 1,620 ft³
1,620 × 10 ACH ÷ 60 = 270 CFM

Worked Examples: Gas, Electric and Induction

Do Not Forget Noise, Filters and the Speeds You Will Actually Use

The most powerful speed is useful only if you are willing to turn it on. A hood that is painfully loud at the airflow you need may spend its life on low speed while smoke escapes around it. In North America, hood noise is often listed in sones; elsewhere you may see dB(A). Compare sound at realistic operating speeds when the manufacturer publishes it.

• Choose multiple useful speed steps rather than focusing only on the maximum setting.
• Check whether airflow and sound ratings are certified or independently tested where applicable.
• Make sure grease filters are easy to remove and clean; a neglected filter adds resistance and becomes a maintenance problem.
• For recirculating models, price and availability of charcoal or odour filters matter over the life of the hood.
• Check lighting quality, controls and filter indicators because the hood is used every time you cook, not only during dramatic frying.
• Compare the hood's required electrical supply and installation instructions before cabinets and finishes are complete.

Common Range Hood Sizing Mistakes

Range Hood Size and CFM FAQ

Final Range Hood Buying Checklist

• Cooktop or range width is confirmed from the actual appliance.
• Wall, peninsula or island location is known.
• The hood is at least as wide as the cooking surface unless the approved design says otherwise.
• The width-based CFM starting point has been calculated.
• For gas, total burner BTU and the appliance manufacturer's ventilation guidance have been checked.
• Heavy frying, searing, wok, grill or griddle use has been considered.
• The selected hood can be installed within its approved height range.
• The duct diameter or rectangular size matches the manufacturer's requirement.
• The route to outdoors is short enough and uses as few restrictions as practical.
• The wall or roof termination is compatible with the system.
• Rated airflow, sound and fan-speed data have been compared rather than only maximum CFM.
• Make-up-air and pressure-balance requirements have been checked before selecting a high-CFM hood.
• Fuel-burning appliances and fireplaces have been considered as part of the pressure-safety review.
• Recirculating filtration has not been mistaken for outdoor exhaust.
• Filter cleaning and replacement are practical for everyday use.

Technical References Worth Checking

The right range hood is the one that captures your cooking plume at a usable noise level and can move the required air through the duct system your house can actually support. Start with width and location, add the gas-output check when relevant, then verify hood geometry, mounting height, ducting and replacement air before paying for a larger blower.