Velocity & Pressure Drop Calculator

Estimate hydraulic pressure drop through a straight hose or pipe using the Darcy–Weisbach equation. Enter the actual inside diameter, not nominal pipe or hose size.

Corrugated metal hose note: pressure loss depends strongly on hose series, corrugation geometry, pitch, convolution depth, braid, and fitting geometry. For corrugated hose, use a validated effective roughness or manufacturer pressure-drop basis. Do not treat a smooth-tube result as a certified metal-hose rating.
Volumetric flow through the assembly.
Use measured or product-specific flow ID.
Straight developed length used for wall-friction loss.
Optional combined K for fittings, entrances, exits, valves, or other local losses.
Preset only supplies density and viscosity inputs.
Default is a smooth metallic-pipe approximation. Replace with validated product-specific roughness where available.

Method: Darcy–Weisbach. Laminar flow uses f = 64/Re. Turbulent flow uses the Swamee–Jain explicit approximation. Transitional flow is reported as transitional and should be reviewed carefully. Outputs are preliminary engineering estimates.

Use the Result for Product Review

For a metal hose assembly, submit the calculated flow condition together with hose size, hose series, overall length, end fittings, pressure, temperature, media, and installation geometry so the assembly can be checked against product-specific pressure-drop and velocity limits.

Request Metal Hose Engineering Review

Velocity, Reynolds Number & Pressure Drop for Hose and Pipe

This calculator uses the Darcy–Weisbach method for straight-run friction loss and allows a combined minor-loss coefficient for fittings and local losses. Enter the actual internal flow diameter, not nominal hose or pipe size, because velocity and pressure loss are highly sensitive to inside diameter.

Corrugated metal hose requires product-specific flow data

A corrugated hose can create substantially different hydraulic resistance than smooth pipe. Corrugation profile, pitch, convolution depth, braid, fittings, and actual flow diameter all affect pressure loss. Use a validated effective roughness or manufacturer flow basis when applying the result to a specific metal hose assembly.

Use the calculated flow condition to evaluate

  • Fluid velocity through the selected hose or pipe ID.
  • Reynolds number and laminar, transitional, or turbulent flow regime.
  • Straight-run friction loss and added fitting or valve losses.
  • Total pressure drop and available system pressure margin.
  • Whether a larger hose ID or different assembly geometry should be reviewed.

Browse the Metal Hose Assembly Catalog, review Metal Hose Pressure & Temperature Selection, or return to Engineering Calculators.