Formula & worked example
ΔP=f(L/D)ρv²/2; actual line flow≈free-air flow×Patm/Pabs.
100 SCFM through a long small-bore line can create a disproportionate loss because velocity and friction rise sharply as diameter falls.
Plant engineering calculator · Updated Sep 17, 2026
Compressed Air Pressure Drop Calculator — Darcy Friction, Velocity & Downstream Pressure
Estimate compressed-air pipe friction with pressure-corrected actual flow, Reynolds number and Darcy-Weisbach loss. Returns velocity, Reynolds number, friction factor, pressure drop and downstream pressure.
Inputs
Live result
Actual line flow 0.03023514 m³/s
Velocity 14.91745 m/s
Reynolds number 378,495.8
Darcy friction factor 0.02004729
Pipe friction drop 5.380751 psi
Downstream pressure 94.61925 psig
Assumptions & limits
- Uses an isothermal single-density screening approximation at entered line pressure.
- Add dryer, filter, regulator, hose and fitting losses separately or through equivalent length.
Frequently asked questions
What does this Compressed Air Pressure Drop Calculator calculate?
Estimate compressed-air pipe friction with pressure-corrected actual flow, Reynolds number and Darcy-Weisbach loss. Returns velocity, Reynolds number, friction factor, pressure drop and downstream pressure.
Can I use the result for final equipment selection?
Use it for screening, benchmarking and option comparison. Final selection should use measured conditions, manufacturer performance data and applicable engineering standards.
Why are assumptions shown beside the calculation?
Plant calculations change materially with pressure basis, reference conditions, efficiencies and operating profile. Explicit assumptions make the result auditable instead of hiding those choices.