Compressed Air Pipe Size Calculator
Pipe diameter for a compressed air line.
Enter your values
Enter the flow in SCFM.
Enter the line pressure in psi.
Enter the pipe length in ft.
Enter the pipe inside diameter in in.
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.
- Pressure drop
- 346.47 psi
- Verdict
- Too much — increase pipe size
- Minimum diameter for 2 psi
- 2.1 in
- Suggested nominal size
- 1-1/2" or larger
- Velocity guide
- Keep under 20 ft/s in mains
Quick answer
Compressed air lines are sized so total pressure drop stays under about 2 psi from compressor to tool.
drop rises with length and falls with the fifth power of diameter
At a glance
| What it does | Pipe diameter for a compressed air line. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Flow, Line pressure, Pipe length, Pipe inside diameter |
| Main output | Pressure drop |
| Formula | drop rises with length and falls with the fifth power of diameter |
| Cost | Free — no sign-up, no download |
How to use the Compressed Air Pipe Size Calculator
- 1Enter the flow the line must carry and the operating pressure.
- 2Include the full run length plus equivalent length for fittings.
- 3Increase diameter until pressure drop is under 2 psi.
Inputs explained
- Flow(SCFM)
- Enter the flow in SCFM.
- Line pressure(psi)
- Enter the line pressure in psi.
- Pipe length(ft)
- Enter the pipe length in ft.
- Pipe inside diameter(in)
- Enter the pipe inside diameter in in.
Worked example
Using the values the calculator loads with:
Inputs
- Flow40 SCFM
- Line pressure100 psi
- Pipe length100 ft
- Pipe inside diameter0.75 in
Results
- Pressure drop346.47 psi
- VerdictToo much — increase pipe size
- Minimum diameter for 2 psi2.1 in
- Suggested nominal size1-1/2" or larger
- Velocity guideKeep under 20 ft/s in mains
Frequently asked questions
Does 1 psi matter?
Every 2 psi of drop costs about 1% in compressor energy, and tools lose torque quickly below rating.
Loop or dead-end?
A ring main halves the effective length and evens out pressure at every drop.
What do I need to enter into the Compressed Air Pipe Size Calculator?
Just 4 values: flow, line pressure, pipe length, pipe inside diameter. 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 Compressed Air Pipe Size Calculator work out the answer?
Compressed air lines are sized so total pressure drop stays under about 2 psi from compressor to tool. It applies the formula drop rises with length and falls with the fifth power of diameter and shows the working so you can check each step by hand.
Is the Compressed Air Pipe Size 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.