Use this engineering calculation for a transparent preliminary estimate or independent arithmetic check when geometry, materials, loads, operating conditions, and units are defined consistently.

Viscosity Pascal Seconds (Pa·s)

Required number input.

Length Meters (m)

Required number input.

Flow Cubic Meters Per Second (m³/s)

Required number input.

Radius Meters (m)

Required number input.

Laminar pressure drop through a straight circular tube by Hagen–Poiseuille; assumes fully developed Newtonian flow. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Pressure Drop Pascals (Pa)

The resulting pressure drop pascals returned as a number.

• Hydraulic equations require consistent datum, fluid properties, geometry, roughness, flow regime, and loss coefficients. Cavitation, air entrainment, unsteady flow, fittings, sediment, free-surface effects, and pump behavior may require a network or numerical model.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check assumptions against drawings, measurements, current material data, and the applicable design code. Apply required load combinations and safety factors, then obtain qualified review and testing for consequential designs.

• Darcy Weisbach Pressure Drop

  Darcy–Weisbach pressure drop in a straight constant-diameter pipe from a supplied Darcy friction factor; excludes local losses.

• Drag Coefficient Flat Plate

  Average skin-friction coefficient over a smooth flat plate in laminar zero-pressure-gradient flow: Cf=1.328/√ReL.

• Bernoulli Total Head

  Total ideal-flow head as elevation plus pressure head and velocity head; excludes friction and pump terms.