Hydraulic Hose Pressure Drop Calculator

Inputs

Flow rate (Q)

Oil flow through the hose.

L/min

Hose inside diameter (D)

Actual hose bore / inside diameter, not nominal dash size.

Hose length (L)

Total hose length.

Kinematic viscosity (ν)

Oil kinematic viscosity at operating temperature. ISO VG 46 oil is about 46 cSt at 40°C.

cSt

Specific gravity (SG)

Fluid density relative to water. Mineral hydraulic oil is often around 0.85-0.90.

Roughness (ε)

Equivalent internal roughness. Smooth hose is low; old or rough pipe is higher.

Fitting loss coefficient (ΣK)

Sum of minor-loss K values for elbows, adapters, quick couplers and fittings.

Default result

Pressure drop(Δp)

0.4652bar

Pass

f = 0.0659, laminar flow

Also computed

Oil velocity(v)2.351m/s

typical pressure-line range

Reynolds number(Re)971.2

laminar

Power loss(P_loss)0.03101kW

Method notes 3 notes

Darcy-Weisbach: Δp = (f·L/D + ΣK) · ρ·v²/2. Laminar f = 64/Re; turbulent f uses the Swamee-Jain approximation.
Use oil viscosity at operating temperature. Cold oil can be many times more viscous and will drop far more pressure.
The fitting coefficient ΣK is a screening input; vendor pressure-drop curves are better for quick couplers, valves and complex fittings.