Under Cabinet vs Wall Mount Hood Sizes: Fit and Dimension Differences

Why the Mounting Style Changes Everything About Size

The physical size of a range hood is not just about how wide it is. The mounting style determines which dimensions matter most, how the hood attaches to your kitchen, and how much space it occupies. Under cabinet hoods are built to slide beneath an upper cabinet, so their depth and height are tightly constrained. Wall mount hoods stand freely against the wall above a range, so their height and chimney length become the primary variables.

Both styles share a common width measurement: the hood's face should match or slightly exceed the width of your cooktop. But the similarities end there. An under cabinet hood is essentially a box with a flat top, while a wall mount hood is a canopy with a decorative chimney that extends upward. That chimney adds 18 to 36 inches of visible height, which changes how you measure the hood and how it fits into the room.

When comparing sizes, you are really comparing three dimensions: width, depth, and height. For under cabinet hoods, depth is fixed by the cabinet above. For wall mount hoods, height is flexible but limited by ceiling height and duct routing. Understanding which dimension is negotiable and which is fixed will guide every other decision.

Width: The One Dimension That Matches Your Cooktop

Width is the first size you will choose, and it follows the same rule for both hood types: the hood should be at least as wide as the cooking surface, and ideally a few inches wider. Standard cooktops come in 30-inch and 36-inch widths, and range hoods are manufactured to match those exact sizes. You will also find 24-inch hoods for compact kitchens and 42-inch or 48-inch models for pro-style ranges.

A 30-inch hood over a 30-inch cooktop is the minimum acceptable fit. Many manufacturers recommend stepping up one size, so a 36-inch hood over a 30-inch cooktop, because the extra width captures steam and grease from the outer burners more effectively. This is true for both under cabinet and wall mount hoods; the width rule does not change with mounting style.

The practical limit is your cabinet layout. Under cabinet hoods are sandwiched between two upper cabinets, so the available space is fixed by the cabinet run. Wall mount hoods sit in an open wall space, so they can be wider than the cooktop without interfering with cabinets, as long as the chimney has clearance. Measure the gap between cabinets for an under cabinet hood, and the wall space above the range for a wall mount.

Depth: The Under Cabinet Hood's Fixed Constraint

Under cabinet hoods have a depth that is determined by the upper cabinet above them. Standard upper cabinets are 12 inches deep, but some are 15 inches, and a few custom cabinets go deeper. The hood must fit flush against the bottom of the cabinet, so its depth is essentially locked to that dimension. Most under cabinet hoods are built at 17 to 20 inches deep, which covers the standard 12-inch cabinet plus a slight overhang toward the cooktop.

That overhang matters because it positions the hood's capture area closer to the front burners. A hood that is too shallow will not reach far enough forward to catch rising smoke and steam. But you cannot simply buy a deeper hood; it must match the cabinet above, or it will look misaligned and may block the cabinet door from opening.

Wall mount hoods have no such constraint. Their depth is typically 18 to 24 inches, and because they are not attached to a cabinet, you can choose a depth that best covers your cooktop. The tradeoff is visual: a deeper canopy protrudes further into the room, which can feel intrusive in a narrow aisle. For both styles, the hood's depth should cover at least the rear burners and ideally extend to the front edge of the cooktop.

Height and Chimney Length: Wall Mount's Flexible Variable

Height is where the two styles diverge most. Under cabinet hoods have a fixed overall height, usually 6 to 12 inches, because they sit directly against the bottom of the cabinet. The only height adjustment is the duct cover, which is not visible. Wall mount hoods, by contrast, have a chimney that can extend from about 18 inches to over 36 inches, depending on ceiling height and how high you mount the canopy.

The installation height above the cooktop is a separate measurement that applies to both styles. For gas ranges, the bottom of the hood should be 24 to 30 inches above the cooking surface; for electric ranges, 18 to 24 inches. This clearance is not a hood dimension, but it determines how much chimney you need for a wall mount hood and how much space remains between the cabinet and the cooktop for an under cabinet hood.

When choosing a wall mount hood, measure from the cooktop to the ceiling, subtract the recommended clearance, and that tells you the maximum chimney length you can use. A hood with a 36-inch chimney will not fit under a standard 8-foot ceiling if you also need 30 inches of clearance. Under cabinet hoods avoid this issue entirely because they have no chimney, which is why they are the default choice for kitchens with soffits, low ceilings, or cabinets that extend to the ceiling.

Ducting and Clearance: Hidden Size Requirements

The hood's visible size is only part of the fit. Both styles require ducting that runs from the top of the hood to the outside, and the duct size must match the hood's CFM rating. A 400 CFM hood typically needs a 6-inch round duct, while higher-capacity hoods may need 8-inch or 10-inch ducting. The duct path takes up space inside the wall or ceiling, which can affect where you can install the hood.

Under cabinet hoods are easier to duct because they sit directly under a cabinet, and the duct can run straight up through the cabinet and into the ceiling. However, the cabinet above must have room for the duct, which may reduce storage space. Wall mount hoods route ducting through the chimney, which is visible, so the duct is hidden but the chimney must be sized to accommodate it.

Clearance is another hidden size factor. The hood needs a few inches of space on each side for airflow and maintenance access, and the duct must avoid electrical wires and plumbing. For wall mount hoods, the chimney must not interfere with cabinet doors or upper cabinets on either side. For under cabinet hoods, the hood's width must fit between two cabinets with at least a half-inch gap on each side for installation. Measure these clearances before you buy, not after.

Which Size Fits Your Kitchen: A Practical Checklist

Start by measuring your cooktop width. This sets the minimum hood width for both styles. Then measure the distance from the cooktop to the ceiling, and the distance from the cooktop to the bottom of the upper cabinets. If the ceiling is higher than the cabinet bottom, you have room for a wall mount hood. If the cabinets are close to the cooktop, an under cabinet hood is the only option that will fit.

For an under cabinet hood, measure the width between the two upper cabinets and the depth of the cabinet above. These two numbers define the maximum hood size. For a wall mount hood, measure the wall space above the range and the ceiling height. Subtract the recommended clearance from the cooktop to the hood bottom, and the remaining distance is the maximum chimney length.

Finally, check the duct path. Look above the ceiling and inside the wall to see if a duct can run to the outside. If the duct run is long or has many bends, you may need a larger duct, which changes the hood's connection size. Write down your measurements and compare them to the manufacturer's spec sheet for each hood you consider. The right size is the one that fits your kitchen's fixed dimensions, not the one that looks best in a showroom.