Welding Booth Ventilation Calculator
Local exhaust airflow for a welding booth.
Enter your values
Choose one of: Flexible extraction arm, Downdraft/backdraft bench.
Enter the arm distance from arc in in.
Enter the bench width in ft.
Enter the bench depth in ft.
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.
- Extraction arm airflow
- 500 CFM
- Capture distance
- 12 in
- Guidance
- Keep hood inlet within 12-18 in of the arc for effective capture
Quick answer
Welding fume extraction typically needs 150-350 CFM per welder for a flexible capture arm positioned close to the arc, or 100-150 CFM per sq ft of a backdraft bench plenum.
CFM = capture area x capture velocity
At a glance
| What it does | Local exhaust airflow for a welding booth. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Capture method, Arm distance from arc, Bench width, Bench depth |
| Main output | Extraction arm airflow |
| Formula | CFM = capture area x capture velocity |
| Cost | Free — no sign-up, no download |
How to use the Welding Booth Ventilation Calculator
- 1Choose flexible extraction arm or a fixed downdraft/backdraft bench.
- 2For an arm, enter its distance from the arc — closer is far more effective.
- 3For a bench, enter its working area to size the plenum airflow.
Inputs explained
- Capture method
- Choose one of: Flexible extraction arm, Downdraft/backdraft bench.
- Arm distance from arc(in)
- Enter the arm distance from arc in in.
- Bench width(ft)
- Enter the bench width in ft.
- Bench depth(ft)
- Enter the bench depth in ft.
Worked example
Using the values the calculator loads with:
Inputs
- Capture methodFlexible extraction arm
- Arm distance from arc12 in
- Bench width4 ft
- Bench depth3 ft
Results
- Extraction arm airflow500 CFM
- Capture distance12 in
- GuidanceKeep hood inlet within 12-18 in of the arc for effective capture
Frequently asked questions
Why is distance so critical for arms?
Capture airflow needed rises with roughly the square of the distance from the source, so doubling distance can quadruple the CFM needed.
Do I need a fume filter or can I exhaust outside?
Either works; filtered recirculation units need periodic cartridge replacement and monitoring.
What do I need to enter into the Welding Booth Ventilation Calculator?
Just 4 values: capture method, arm distance from arc, bench width, bench depth. 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 Welding Booth Ventilation Calculator work out the answer?
Welding fume extraction typically needs 150-350 CFM per welder for a flexible capture arm positioned close to the arc, or 100-150 CFM per sq ft of a backdraft bench plenum. It applies the formula CFM = capture area x capture velocity and shows the working so you can check each step by hand.
Is the Welding Booth Ventilation 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.