Two ways to size a range hood — cooktop width for electric, total BTU for gas
Electric hoods size by cooktop width, gas by total BTU — take the larger, add 25% for an island. The code floor is a flat 100 CFM.
What this diagram shows
An electric cooktop icon with a width dimension and a gas cooktop icon with burner flames on the left. On the right, two method cards: the width method (100 CFM per 12 inches of cooktop, so a 30-inch cooktop needs 250 CFM) and the BTU method (1 CFM per 100 BTU, so 60,000 BTU needs 600 CFM). A green banner says to take the larger of the two and add 25 percent for an island, over an amber code floor of 100 CFM for a vented hood.
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Range Hood CFM Calculator
Free range hood CFM calculator: size by width or BTU, see it vs the code minimum, and learn if you need makeup air (the 400 CFM rule). No signup.
