Hazen–Williams Head Loss Calculator
Friction loss for water pipes by the Hazen–Williams formula with your C coefficient.
Hazen–Williams is water-only (5–25 °C) but needs no viscosity or iteration — why fire protection (NFPA 13) and waterworks still run on it.
Formula
Hazen–Williams Head Loss Calculator is a free hazen williams 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 Hazen–Williams Head Loss Calculator
Friction loss for water pipes by the Hazen–Williams formula with your C coefficient. The calculation implements h_f = 10.67·L·Q^1.852 / (C^1.852·D^4.87) (AWWA M11; NFPA 13 hydraulic calculations). Hazen–Williams is water-only (5–25 °C) but needs no viscosity or iteration — why fire protection (NFPA 13) and waterworks still run on it.
How to use Hazen–Williams Head Loss Calculator
- 1Enter Flow rate in L/s.
- 2Enter Pipe inner diameter in mm.
- 3Enter Pipe length in m.
- 4Enter Hazen–Williams C (PVC 150 · copper 135 · new steel 120 · old cast iron 80–100).
- 5Read Head loss, Loss per 100 m instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Hazen–Williams Head Loss Calculator?
- ✓Implements the standard formula — h_f = 10.67·L·Q^1.852 / (C^1.852·D^4.87)
- ✓Reference cited on-page: AWWA M11; NFPA 13 hydraulic calculations
- ✓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 Hazen–Williams Head Loss Calculator use?+
It computes h_f = 10.67·L·Q^1.852 / (C^1.852·D^4.87), per AWWA M11; NFPA 13 hydraulic calculations. 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?+
Hazen–Williams is water-only (5–25 °C) but needs no viscosity or iteration — why fire protection (NFPA 13) and waterworks still run on it.
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 Hazen–Williams Head Loss Calculator 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.
Related Engineering tools
Reynolds Number Calculator
Compute Re from density, velocity, pipe diameter and viscosity — with instant laminar/turbulent classification.
● LiveLaminar vs Turbulent Flow Classifier
Classify hydraulic-oil or process-fluid flow regime from kinematic viscosity, line velocity and tube bore.
● LiveBernoulli Equation Solver
Solve downstream pressure between two points from velocities, elevations and fluid density (ideal, lossless).
● Live