Pipe Flow Calculator
Enter fluid properties, pipe size/roughness, length, and velocity to estimate losses.
How to Use This Calculator
1
Enter fluid properties
Provide ρ and μ at the operating temperature.
2
Enter pipe data
Diameter, length, and absolute roughness ε.
3
Enter velocity
Press Calculate to view Re, f, head loss, and ΔP.
Formula
ΔP = f (L/D) (ρ V² / 2)
Where: f is Darcy friction factor; for turbulent flow, Swamee–Jain: f = 0.25 / [log10(ε/(3.7D)+5.74/Re^0.9)]².
Example: ρ=1000 kg/m³, μ=0.001 Pa·s, D=0.05 m, L=50 m, ε=0.00015 m, V=2 m/s ⇒ Re=100,000, f≈0.020, hf≈ 2.04 m, ΔP≈ 20 kPa.
Frequently Asked Questions
What about fittings and valves?
Minor losses are not included. Add K v²/(2g) terms per component or equivalent length.
Laminar flow?
For Re < 2300, f = 64/Re and ΔP is exact for straight, fully-developed laminar flow.