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

Darcy Friction Factor

Required number input.

Length Meters (m)

Required number input.

Hydraulic Diameter Meters (m)

Required number input.

Density Kg Per M3 (kg/m³)

Required number input.

Velocity Meters Per Second (m/s)

Required number input.

Straight-duct Darcy friction pressure loss f(L/Dh)(ρv²/2) with supplied friction factor and hydraulic diameter; excludes fittings. 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 Loss Pascals (Pa)

The resulting pressure loss pascals returned as a number.

• Duct pressure loss depends on actual dimensions, roughness, air properties, Reynolds number, fittings, transitions, leakage, system effect, and fan operating point. Equivalent-length shortcuts require compatible fittings and velocity ranges.
• 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.

• Bernoulli Total Head

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

• Forging Force Approx

  First-pass forging force from projected contact area, average flow stress and a supplied dimensionless shape/friction factor.