Commercial Hood Linear Foot Calculator
Total exhaust CFM from multiple hood sections.
Enter your values
Enter the section 1 length in ft.
Choose one of: Light, Medium, Heavy, Extra heavy.
Enter the section 2 length in ft.
Choose one of: Light, Medium, Heavy, Extra heavy.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 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)
At a glance
| What it does | Total exhaust CFM from multiple hood sections. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Section 1 length, Section 1 duty, Section 2 length, Section 2 duty |
| Main output | Total exhaust airflow |
| Formula | Total CFM = sum(length_i x rate_i) |
| Cost | Free — no sign-up, no download |
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.
Inputs explained
- Section 1 length(ft)
- Enter the section 1 length in ft.
- Section 1 duty
- Choose one of: Light, Medium, Heavy, Extra heavy.
- Section 2 length(ft)
- Enter the section 2 length in ft.
- Section 2 duty
- Choose one of: Light, Medium, Heavy, Extra heavy.
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.
What do I need to enter into the Commercial Hood Linear Foot Calculator?
Just 4 values: section 1 length, section 1 duty, section 2 length, section 2 duty. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Commercial Hood Linear Foot Calculator work out the answer?
Total commercial hood exhaust is the sum of each hood section's length multiplied by its duty-specific CFM per linear foot rate. It applies the formula Total CFM = sum(length_i x rate_i) and shows the working so you can check each step by hand.
Is the Commercial Hood Linear Foot Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.