Pipe Flow Pressure Drop Calculator

Inputs

Flow rate (Q)

Volumetric flow through the pipe.

L/min

Pipe inside diameter (D)

Actual inside diameter, not nominal pipe size.

Pipe length (L)

Straight equivalent pipe length.

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.

Roughness (epsilon)

Equivalent internal roughness. Smooth plastic/copper is low; rough steel is higher.

Fitting loss coefficient (sum K)

Sum of minor-loss K values for elbows, tees, valves and fittings.

Default result

Pressure drop(dp)

0.4334bar

f = 0.0218, turbulent flow

Also computed

Head loss(h)4.429m

Pipe velocity(v)1.698m/s

Reynolds number(Re)42,360

turbulent

Darcy friction factor(f)0.02178

Hydraulic power loss(P_loss)0.03612kW

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.