Restaurant Exhaust CFM Calculator
Commercial kitchen hood exhaust airflow.
Enter your values
ⓘ Live results
Results
- Exhaust airflow
- 3,000 CFM
- Rate
- 300 CFM per linear foot
- Makeup air (80%)
- 2,400 CFM
- Duct area at 1800 FPM
- 1.67 sq ft
- Fan static allowance
- 1.0 - 1.5 in wc typical
Quick answer
Commercial hood exhaust is sized in CFM per linear foot of hood, rising with appliance duty from light to extra heavy.
CFM = hood length x CFM per linear foot
How to use the Restaurant Exhaust CFM Calculator
- 1Measure the hood length and identify the heaviest appliance under it.
- 2Choose the hood style — island hoods need substantially more air.
- 3Provide 80-90% of the exhaust as tempered makeup air.
Worked example
Using the values the calculator loads with:
Inputs
- Hood length10 ft
- Hood typeWall-mounted canopy
- Appliance dutyMedium (fryers, ranges)
Results
- Exhaust airflow3,000 CFM
- Rate300 CFM per linear foot
- Makeup air (80%)2,400 CFM
- Duct area at 1800 FPM1.67 sq ft
- Fan static allowance1.0 - 1.5 in wc typical
Frequently asked questions
Why is island so much higher?
There are no side walls to contain the plume, so cross drafts pull effluent out.
Can I undersize to save energy?
No — undersized hoods spill grease-laden vapour into the kitchen and fail inspection.
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.