Island Hood CFM Calculator
Exhaust airflow for an island kitchen hood.
Enter your values
ⓘ Live results
Results
- Exhaust airflow
- 3,200 CFM
- Rate used
- 400 CFM/ft
- Makeup air (90%)
- 2,880 CFM
- Duct at 1800 FPM
- 1.78 sq ft
- Round duct dia
- 18.1 in
Quick answer
Island canopy hoods are sized at 250-700 CFM per linear foot of hood depending on appliance duty, roughly 50% more than an equivalent wall hood.
CFM = hood length x CFM per linear foot (island rate)
How to use the Island Hood CFM Calculator
- 1Measure hood length over the cooking equipment.
- 2Pick the heaviest appliance duty beneath the hood.
- 3Provide tempered makeup air at 85-95% of exhaust to avoid depressurising the kitchen.
Worked example
Using the values the calculator loads with:
Inputs
- Hood length8 ft
- Appliance dutyMedium duty
Results
- Exhaust airflow3,200 CFM
- Rate used400 CFM/ft
- Makeup air (90%)2,880 CFM
- Duct at 1800 FPM1.78 sq ft
- Round duct dia18.1 in
Frequently asked questions
Why do island hoods need more air?
There are no side walls to contain the thermal plume, so cross-drafts pull effluent out from all four sides.
Can I add side panels?
Yes — end panels or a valance can cut required CFM by capturing more of the plume.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.