Pipe Flow Pressure Drop Calculator
SI
Imp
Imperial
Inputs
View results
Flow rate
(Q)
Volumetric flow through the pipe.
L/min
Pipe inside diameter
(D)
Actual inside diameter, not nominal pipe size.
mm
Pipe length
(L)
Straight equivalent pipe length.
m
Fluid density
(rho)
Water is about 998 kg/m^3 near room temperature.
kg/m³
Dynamic viscosity
(mu)
Water is about 1 cP near room temperature. Glycol mixes can be much higher.
cP
Roughness
(epsilon)
Equivalent internal roughness. Smooth plastic/copper is low; rough steel is higher.
mm
Fitting loss coefficient
(sum K)
Sum of minor-loss K values for elbows, tees, valves and fittings.
Results
Default result
Edit inputs
Pressure drop
(dp)
0.4334
bar
f = 0.0218, turbulent flow
Also computed
Head loss
(h)
4.429
m
Pipe velocity
(v)
Pass
1.698
m/s
Reynolds number
(Re)
42,360
turbulent
Darcy friction factor
(f)
0.02178
Hydraulic power loss
(P_loss)
0.03612
kW
Method notes
3 notes
Darcy-Weisbach: dp = (f*L/D + sum K) * rho*v^2/2. Laminar f = 64/Re; turbulent f uses Swamee-Jain.
Use actual pipe ID and fluid viscosity at operating temperature. Nominal pipe size alone is not enough.
This is a piping screen only. Final plumbing, hydronic or process designs still need adopted code, manufacturer data, pump curves, valves, strainers, water hammer, erosion/corrosion and balancing checks.
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