How many CFM does a kitchen exhaust fan need?
A local kitchen exhaust must move at least 100 cfm intermittently or 25 cfm continuously, vented outdoors (IRC Table M1507.3).
Where a local kitchen exhaust system is installed, the IRC sets a minimum airflow of 100 cfm for intermittent operation or 25 cfm for continuous operation, per Table M1507.3.
The exhaust must discharge directly to the outdoors — not into an attic, crawl space, or other interior space. (In the 2018 and later IRC these kitchen rates moved to Section M1505.)
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Ask Donnie →General information based on the International Residential Code (a model code). This is AI assistance to verify — not legal advice. Confirm the adopted edition and any local amendments with your local building department (AHJ) and a licensed professional before you build.