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hydraulics / closed conduits

Hazen-Williams pipe head loss calculator.

Estimate distributed friction head loss and its pressure equivalent from full-pipe flow, pipe geometry, a Hazen-Williams C value, and fluid density.

read the result

Keep the empirical coefficient visible.

Hazen-Williams is a convenient empirical relationship for estimating friction loss in water-like full-pipe flow. The coefficient C is not a constant of nature: it reflects the selected pipe material, age, internal condition, and the project basis.

Governing equations

In the SI form used here, hf = 10.67LQ1.852/(C1.852D4.87). Mean velocity is V = Q/A with A = πD2/4, and the pressure equivalent is Δp = ρghf.

What the number does not include

  • Fittings, valves, entries, exits, and equipment losses are excluded.
  • Static elevation, pumps, residual pressure, air release, transients, and water hammer are excluded.
  • Confirm that the full-pipe condition and the water-temperature/viscosity basis are suitable for the selected method.
  • Compare with Darcy-Weisbach when friction-factor, roughness, and Reynolds-number effects need to be explicit.