Range Hood Sizing Guide: Matching Hood Width and CFM to Your Range

Why Hood Width Should Match or Exceed Your Range Width

The first rule of range hood sizing is that the hood should be at least as wide as your cooktop, and ideally a few inches wider. A hood that is narrower than the range cannot capture the rising steam, smoke, and grease particles that drift outward from the outer burners, especially when you use the rear burners. For most kitchens, a 30-inch range pairs with a 30-inch hood, while a 36-inch range calls for a 36-inch hood, but going wider—say, a 42-inch hood over a 36-inch range—improves capture without looking out of place.

Why does extra width matter? Cooking plumes expand as they rise. If your hood is the same width as the range, the outer edges of the plume can escape before reaching the filter, particularly if the hood is mounted high or the cooking is vigorous. A hood that is 3 to 6 inches wider than the cooktop provides a margin of error, catching more of the plume before it spreads into the room. This is why many manufacturers and kitchen designers recommend sizing up, not down, when you are between two standard sizes.

If you have an island or a wall-mounted cooktop with no cabinets to contain the plume, wider is even more important. In open layouts, cross-drafts from windows, doors, or HVAC vents can push the plume sideways. A wider hood gives you more forgiveness in these conditions. Conversely, a hood that is dramatically wider—say, 12 inches or more—can look top-heavy over a small range, so balance visual proportion with practical capture when you choose.

Measuring Your Range and Kitchen Layout for a Correct Fit

Before you shop, measure the width of your range or cooktop from outer edge to outer edge. Use a metal tape measure, and record the dimension in inches. Standard residential ranges are 30 or 36 inches wide, but professional-style ranges can be 48 or even 60 inches, so do not assume—measure. Also measure the depth of the cooktop, because a hood that is too shallow relative to the front burners will let steam escape forward.

Next, measure the distance from the cooktop surface to the bottom of the hood. For gas ranges, most manufacturers recommend 24 to 30 inches of clearance; for electric, 18 to 24 inches is common. This height affects both safety and performance. If you mount the hood too high, the fan has to work harder to capture the plume; if too low, it can be a head hazard and may not meet building codes. Check your hood's installation manual for the exact range, and factor in the height of the tallest cook in your household.

Also note the width of the cabinet above the range. If you have a 36-inch-wide upper cabinet, a 36-inch hood will fit flush, but a 42-inch hood may overhang the cabinet edges. For ducted hoods, you also need to account for the duct run: measure the distance from the hood to the exterior wall or roof, and note any turns, because longer or more angled duct runs reduce airflow and may require a larger CFM rating to compensate.

Calculating CFM: The Airflow Your Kitchen Needs

CFM, or cubic feet per minute, measures how much air the hood fan moves. Too little CFM means smoke and odors linger; too much can create negative pressure, pulling air down the chimney or making doors hard to open. The standard rule for gas and electric ranges is to divide the BTU output of your burners by 100 to get a minimum CFM. For example, a range with 40,000 total BTUs needs at least 400 CFM. However, this rule only accounts for burner output, not the size of the kitchen.

A more complete approach uses the kitchen's volume. Multiply the room's length, width, and ceiling height (in feet) to get cubic feet. For a kitchen with a closed door, you want the hood to exchange the air about 15 times per hour, so multiply the volume by 15 and divide by 60 to get the minimum CFM. For example, a 10x12-foot kitchen with 8-foot ceilings has 960 cubic feet; 960 times 15 divided by 60 equals 240 CFM. But if you have an open floor plan, you must include the adjacent living space in the volume, because the hood is venting the whole area, not just the kitchen.

Cooking style also matters. If you regularly sear steaks, fry foods, or use a wok at high heat, add 100 to 200 CFM to the calculated minimum. If you have a gas range that produces a lot of smoke, you may need a hood rated for more than the minimum to keep up. As a general guideline for a typical home cook, a 30-inch range usually pairs with 400 to 600 CFM, while a 36-inch range often needs 600 to 900 CFM. Professional-style ranges with high BTU burners may require 1,000 CFM or more, but check local building codes, because some jurisdictions require makeup air systems for exhaust fans above a certain CFM to prevent backdrafting of combustion gases.

Ducted vs. Ductless: How Venting Type Affects Size Choice

Your hood's venting type changes how you think about both width and CFM. A ducted (vented) hood exhausts air to the outside through a duct, and it is the most effective at removing smoke, moisture, and odors. Because the air leaves the house, the fan does not have to work against recirculated air, so you can often choose a slightly lower CFM for the same performance. Ducted hoods are the standard for serious cooks, but they require a path to the exterior, which may not be possible in every kitchen.

A ductless (recirculating) hood passes air through a charcoal filter to remove grease and odors, then blows the cleaned air back into the room. These hoods are easier to install because they need no ductwork, but they are less effective at removing moisture and heat, and they require more frequent filter replacement. Because ductless hoods have to overcome the resistance of the charcoal filter, they typically need a higher CFM rating to achieve the same air-clearing effect as a ducted model. When comparing, look for the hood's CFM rating at the point of use, not just the motor's maximum rating, which is often measured without the filter in place.

For both types, the width and CFM should be matched to your range, but ductless systems are more forgiving if you cannot install a wide hood because the filter only covers part of the hood's width. However, a wider hood still captures more of the plume, so if you have the space and the ducting, a ducted hood that is 3 to 6 inches wider than the range is the best choice for performance. If you are replacing an existing hood, measure the current duct size (usually 6 or 8 inches round, or rectangular) and keep it consistent to avoid reducing airflow.

Common Sizing Mistakes and How to Avoid Them

One frequent mistake is choosing a hood that is too small for the range, either because the buyer focuses on price or because the kitchen has a narrow opening. A 30-inch hood over a 36-inch range will leave the front and side burners largely unprotected, and smoke will spill into the room. Another mistake is picking a hood with a very high CFM rating without checking the noise level. A 1,200 CFM hood running at full speed can be as loud as a lawnmower, which is unpleasant in a living space. Look for the sone rating (a measure of loudness); under 3 sones is quiet, 3 to 6 is moderate, and above 6 is loud.

Another error is ignoring the height of the ceiling. If you have a 9-foot or higher ceiling, the hood must be mounted higher, which reduces its capture efficiency. You may need a taller hood (in terms of width) or a higher CFM to compensate. Conversely, a hood that is too large for a small kitchen can overwhelm the room visually and, if it has a high CFM, create negative pressure that pulls air from the outside, causing drafts or backdrafts. In tight homes, this is a real concern, and you may need a makeup air damper or an ERV system to balance the pressure.

Finally, do not forget the shape of the hood. A wall-mounted canopy or chimney hood is the most common, but under-cabinet hoods are narrower and may not cover the full width of a large range. Downdraft vents, which pull air from the cooktop surface, are an option for islands without a ceiling, but they are generally less effective than overhead hoods for capturing rising smoke, and they require careful CFM selection to work at all. Always cross-check the hood's dimensions against your range's width and your kitchen's layout before buying.