Hydraulics & drainage · Pipes & hydraulic structures

Pressure pipe head loss (Darcy & Hazen–Williams) calculator

Friction factor, head loss by Darcy–Weisbach and Hazen–Williams, and velocity for a full pressure pipe.

Standard: Darcy–Weisbach with Swamee–Jain · Hazen–Williams

Inputs in the worked example

The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.

Diagram for the worked example

Velocity = 50/1000/(PI()*(250/1000)^2/4) = 1.0186 m/s
Reynolds = 1.0186*250/1000/1.000e-6 = 2.546e+5
Swamee–Jain f = 0.25/LOG10(0.15/(3.7*250)+5.74/2.546e+5^0.9)^2 = 0.019088
Darcy hf = f L V²/(2gD) = 0.019088*800*1.0186^2/(2*9.81*250/1000) = 3.2301 m
Hazen–Williams 10.67 L Q^1.852/(C^1.852 D^4.87) = 10.67*800*(50/1000)^1.852/(130^1.852*(250/1000)^4.87) = 3.4575 m

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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.