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Pipe Pressure Drop Calculator
Enter pipe data and flow — pressure drop updates instantly.
Formula
hf = f · (L/D) · v²/2g | hm = ΣK · v²/2g | Δp = ρ·g·(hf + hm)
Recommended Velocities
| Line | Velocity (m/s) |
|---|---|
| Pump suction | 1.0 – 2.0 |
| Pump discharge | 2.0 – 4.0 |
| Water mains | 1.0 – 2.5 |
| Steam lines | 20 – 40 |
Typical Friction Factors
| Pipe | f |
|---|---|
| PVC / PE (smooth) | 0.015 |
| Commercial steel | 0.020 |
| Galvanized | 0.025 |
| Old / scaled | 0.035+ |
FAQ
How accurate is a constant f?
f varies slightly with Reynolds number and roughness. For design estimates 0.02 (steel) is standard; refine with our Reynolds calculator if needed.
Why is my pressure drop so high?
Check velocity first — losses scale with v². Halving the diameter multiplies friction roughly 10× for the same flow.