Pipe Friction Loss Calculator (Darcy–Weisbach)
Head loss in a pipe with the friction factor solved automatically (Swamee–Jain) from roughness and Reynolds number.
Swamee–Jain reproduces the Colebrook–Moody chart within ±1% for 5×10³ < Re < 10⁸ — no iteration needed.
Formula
Pipe Friction Loss Calculator (Darcy–Weisbach) is a free pipe friction loss for pump engineers, plumbers and plant designers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Pipe Friction Loss Calculator (Darcy–Weisbach)
Head loss in a pipe with the friction factor solved automatically (Swamee–Jain) from roughness and Reynolds number. The calculation implements h_f = f·(L/D)·V²/2g; f via Swamee–Jain (full turbulent range) (Swamee & Jain (1976), J. Hydraulics Div. ASCE; Moody chart — Crane TP-410). Swamee–Jain reproduces the Colebrook–Moody chart within ±1% for 5×10³ < Re < 10⁸ — no iteration needed.
How to use Pipe Friction Loss Calculator (Darcy–Weisbach)
- 1Enter Flow rate in L/s.
- 2Enter Pipe inner diameter in mm.
- 3Enter Pipe length in m.
- 4Enter Roughness ε in mm (Commercial steel 0.045 · PVC 0.0015 · cast iron 0.26).
- 5Read Head loss, Friction factor f, Velocity instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Pipe Friction Loss Calculator (Darcy–Weisbach)?
- ✓Implements the standard formula — h_f = f·(L/D)·V²/2g; f via Swamee–Jain (full turbulent range)
- ✓Reference cited on-page: Swamee & Jain (1976), J. Hydraulics Div. ASCE; Moody chart — Crane TP-410
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Pipe Friction Loss Calculator (Darcy–Weisbach) use?+
It computes h_f = f·(L/D)·V²/2g; f via Swamee–Jain (full turbulent range), per Swamee & Jain (1976), J. Hydraulics Div. ASCE; Moody chart — Crane TP-410. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
Swamee–Jain reproduces the Colebrook–Moody chart within ±1% for 5×10³ < Re < 10⁸ — no iteration needed.
Can I use this for pump selection?+
Use it to establish the duty (flow, head, NPSH, power) and then pick a pump whose curve passes through that point near best efficiency. The tool gives you the engineering numbers a supplier will ask for.
Is the Pipe Friction Loss Calculator (Darcy–Weisbach) free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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