Vacuum CFM Calculator
Airflow and pipe size for a vacuum system.
Enter your values
Enter the hose diameter in in.
Enter the air velocity in FPM.
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.
- Airflow
- 136 CFM
- Hose area
- 0.0341 sq ft
- Velocity
- 4,000 FPM
- Chip conveying minimum
- 3500-4000 FPM
- In m³/h
- 232
Quick answer
Vacuum airflow equals hose cross-sectional area multiplied by air velocity, the same relationship as any duct.
CFM = area (sq ft) x FPM
At a glance
| What it does | Airflow and pipe size for a vacuum system. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Hose diameter, Air velocity |
| Main output | Airflow |
| Formula | CFM = area (sq ft) x FPM |
| Cost | Free — no sign-up, no download |
How to use the Vacuum CFM Calculator
- 1Measure the hose or pipe inside diameter.
- 2Use 3,500-4,000 FPM to keep chips and dust airborne.
- 3Match the vacuum's rated CFM at your actual static pressure, not free air.
Inputs explained
- Hose diameter(in)
- Enter the hose diameter in in.
- Air velocity(FPM)
- Enter the air velocity in FPM.
Worked example
Using the values the calculator loads with:
Inputs
- Hose diameter2.5 in
- Air velocity4000 FPM
Results
- Airflow136 CFM
- Hose area0.0341 sq ft
- Velocity4,000 FPM
- Chip conveying minimum3500-4000 FPM
- In m³/h232
Frequently asked questions
Why does hose length matter?
Long small-bore hose adds huge resistance — a 2.5 in hose at 30 ft can halve the airflow.
Shop vac vs dust collector?
Shop vacs are high suction, low flow; dust collectors are the opposite and suit large machines.
What do I need to enter into the Vacuum CFM Calculator?
Just 2 values: hose diameter, air velocity. 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 Vacuum CFM Calculator work out the answer?
Vacuum airflow equals hose cross-sectional area multiplied by air velocity, the same relationship as any duct. It applies the formula CFM = area (sq ft) x FPM and shows the working so you can check each step by hand.
Is the Vacuum 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.