Free · Physics models
Hazen Williams Pipe Head Loss
Estimate positive water-pipe head and pressure loss using the empirical Hazen–Williams relation.
- Formula & worked example
- Private in your browser
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Calculator inputs
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How to use this calculator
- Enter the known values in the units shown. Results update as you type.
- Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
- Use the worked example to check the method. Reset restores the starting fields.
Private by default
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Formula and method
A 1 m pipe diameter, 10 m length, 1 m³/s flow and C = 100 yield about 0.02110 m head loss and 0.002070 bar.
h = 10.67 L (Q/C)^1.852 / D^4.8704; Δp = 9810 h.
Worked example
Enter these known values and leave the other values blank.
- Pipe diameter
- 1 m
- Pipe length
- 10 m
- Volumetric flow rate
- 1 m³ / sec
- Pipe roughness coefficient
- 100
- Friction head loss
- 0.021094 m of water
- Pressure loss
- 0.0020693 bar
Assumptions and limitations
- Empirical SI Hazen–Williams estimate for water flow; it is not a general gas, slurry or viscosity model.
- The retained pressure conversion assumes density 1,000 kg/m³ and gravity 9.81 m/s².
- Only pressure and length participate in inverse solutions; the captured one-way power expression does not solve flow, coefficient or diameter.
- Enter known quantities and clear the unknown to use available inverse branches. Locks retain supplied values. Consistency messages cover fully visible equations; identities with hidden dependencies may require a manual consistency check. Preset values are illustrative approximations, and unit selectors preserve the underlying quantity.
Common questions
How do I solve for a different quantity?
Clear that quantity and supply enough independent known values. Some outputs are one-way or tied to a selected preset, so they cannot determine every input.
References
The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.