Welding Fume Extraction CFM Calculator
Capture airflow for a welding hood or arm.
Enter your values
Enter the capture distance in ft.
Enter the hood face area in sq ft.
Enter the capture velocity in FPM.
Choose one of: Yes, No.
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 airflow
- 840 CFM
- Unflanged requirement
- 1,120 CFM
- Saving from flange
- 280 CFM
- At half the distance
- 278 CFM
Working
- 1100 x (10 x 1² + 1.2) = 1,120 CFM
Quick answer
Capture airflow rises with the square of distance, so getting the hood close is far more effective than buying a bigger fan.
CFM = V x (10 x X² + A) for a plain hood
At a glance
| What it does | Capture airflow for a welding hood or arm. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Capture distance, Hood face area, Capture velocity, Flanged hood? |
| Main output | Extraction airflow |
| Formula | CFM = V x (10 x X² + A) for a plain hood |
| Cost | Free — no sign-up, no download |
How to use the Welding Fume Extraction CFM Calculator
- 1Measure how far the hood face sits from the arc or fume source.
- 2Enter the hood face area and required capture velocity — 100 FPM suits welding.
- 3Add a flange to the hood; it cuts required airflow by about 25%.
Inputs explained
- Capture distance(ft)
- Enter the capture distance in ft.
- Hood face area(sq ft)
- Enter the hood face area in sq ft.
- Capture velocity(FPM)
- Enter the capture velocity in FPM.
- Flanged hood?
- Choose one of: Yes, No.
Worked example
Using the values the calculator loads with:
Inputs
- Capture distance1 ft
- Hood face area1.2 sq ft
- Capture velocity100 FPM
- Flanged hood?Yes
Results
- Extraction airflow840 CFM
- Unflanged requirement1,120 CFM
- Saving from flange280 CFM
- At half the distance278 CFM
- 100 x (10 x 1² + 1.2) = 1,120 CFM
Frequently asked questions
Why does distance matter so much?
Required airflow grows with the square of distance, so doubling the gap roughly quadruples the fan you need.
Is general ventilation enough?
No — local exhaust at source is the only reliable control for welding fume.
What do I need to enter into the Welding Fume Extraction CFM Calculator?
Just 4 values: capture distance, hood face area, capture velocity, flanged hood?. 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 Fume Extraction CFM Calculator work out the answer?
Capture airflow rises with the square of distance, so getting the hood close is far more effective than buying a bigger fan. It applies the formula CFM = V x (10 x X² + A) for a plain hood and shows the working so you can check each step by hand.
Is the Welding Fume Extraction CFM 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.