Reading capture area, not a single number
Think of the hood inlet as a window you place above the cooktop. The window must intersect the rising plume’s trajectory. Width increases coverage left-to-right; depth increases coverage front-to-back—often the decisive axis for front burners and for wok cooking that projects heat forward.
Mounting height changes the plume cross-section that enters the hood. The same nominal width behaves differently at 24 inches versus 30 inches above the pans. That is why CFM cannot be evaluated without geometry: airflow through a misaligned inlet is not “wrong air,” but it may be air that misses the smoke.
Island hoods: fewer walls, more freedom for the plume
Wall-mounted hoods sometimes benefit from adjacent cabinetry that helps steer flow. Island configurations expose more sides of the cooktop to the room, and cross-breezes can bend plumes sideways. Designers often specify larger capture areas and careful burner alignment for island cooking—paired with realistic fan speeds people will tolerate, as discussed in noise and behavior.
Front burners vs back burners
Many households use front burners most often. If the hood is shallow or set high, the plume from the front row may travel outside the hood’s projected footprint before it reaches the inlet. That is a layout problem, not a “brand loyalty” problem. If you are also pushing a lot of exhaust CFM, check whether your house can handle it without unintended pressure effects—see makeup air.
When to widen, when to deepen
Widening helps when smoke escapes at the sides. Deepening helps when smoke escapes toward the room or when you cook on front burners with large pans. If you must choose between two imperfect products, the better match is usually the one whose inlet geometry matches your actual burner patterns—not the one with the largest CFM on the label.
Return to the plume
If this page feels like a repeat of capture and plume geometry, that is intentional: the same physics appears in different purchasing decisions. The goal is to build a mental model you can reuse when comparing catalogs, not to memorize a single “correct” hood size.