Commercial Hood Linear Foot Calculator
Total exhaust CFM from multiple hood sections.
Enter your values
ⓘ Live results
Results
- Total exhaust airflow
- 3,400 CFM
- Section 1
- 1,800 CFM
- Section 2
- 1,600 CFM
- Total makeup air (85%)
- 2,890 CFM
- Combined duct at 1800 FPM
- 18.6 in
Quick answer
Total commercial hood exhaust is the sum of each hood section's length multiplied by its duty-specific CFM per linear foot rate.
Total CFM = sum(length_i x rate_i)
How to use the Commercial Hood Linear Foot Calculator
- 1Break the hood line into sections by appliance duty.
- 2Enter each section's length and duty.
- 3Sum the sections to get the total fan and makeup air requirement.
Worked example
Using the values the calculator loads with:
Inputs
- Section 1 length6 ft
- Section 1 dutyMedium
- Section 2 length4 ft
- Section 2 dutyHeavy
Results
- Total exhaust airflow3,400 CFM
- Section 11,800 CFM
- Section 21,600 CFM
- Total makeup air (85%)2,890 CFM
- Combined duct at 1800 FPM18.6 in
Frequently asked questions
Can one fan serve all sections?
Yes, provided the hood has continuous internal ductwork or a common plenum sized for the total CFM.
Do I still need per-section balancing?
Yes — balancing dampers should be set so each section pulls its design airflow.
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.