Size a kitchen range hood. Enter the cooktop width and type to get the recommended hood width and exhaust airflow (CFM).
Recommended Airflow
— CFM
Minimum exhaust airflow.Usage Tip
Match the duct diameter to the blower (commonly 6 to 10″) and keep the run short with smooth elbows. A quieter hood at moderate CFM that you actually run beats a loud one you never turn on.
THE MATH
Electric / induction: CFM = width (ft) × 100
Gas: CFM = total BTU ÷ 100 (at least 100 CFM per foot)
Hood width = cooktop width to cooktop + 6″
Gas: CFM = total BTU ÷ 100 (at least 100 CFM per foot)
Hood width = cooktop width to cooktop + 6″
A hood works best at least as wide as the cooktop, with about 3″ of overhang each side. Airflow scales with cooking power: linear width for electric, burner BTU for gas.
Island hoods are open on all sides and need more airflow than wall or under-cabinet hoods.
Island hoods are open on all sides and need more airflow than wall or under-cabinet hoods.
Vent to the outside whenever possible; recirculating (charcoal-filter) hoods remove far less moisture, grease, and odor.
Above about 400 CFM, many jurisdictions require dedicated makeup air so the exhaust does not depressurize the house (IRC M1503.4) — confirm locally.
Duct size and length matter: undersized or long, twisty ducts choke a high-CFM hood, so keep runs short and straight and match the duct to the blower.
Above about 400 CFM, many jurisdictions require dedicated makeup air so the exhaust does not depressurize the house (IRC M1503.4) — confirm locally.
Duct size and length matter: undersized or long, twisty ducts choke a high-CFM hood, so keep runs short and straight and match the duct to the blower.