Pipe Pressure Drop Calculator

Blog post description.

Wiratama

11/15/20251 min read

Pipe Pressure Drop – Definition

Pipe pressure drop is the loss of pressure that occurs as a fluid flows through a pipe. This pressure reduction results from friction between the fluid and the pipe walls, as well as internal fluid turbulence. Understanding pressure drop is essential for designing piping systems, pump sizing, HVAC ducts, and industrial flow networks.

Background Theory

The most widely used model for head loss in pipe flow is the Darcy–Weisbach equation:

Where:

  • ΔP = pressure drop (Pa)

  • f = friction factor (depends on flow regime & roughness)

  • L = pipe length (m)

  • D = pipe diameter (m)

  • ρ = fluid density (kg/m³)

  • V = flow velocity (m/s)

The friction factor f is influenced by:

  • Flow regime (laminar or turbulent)

  • Pipe roughness

  • Reynolds number

  • Fluid properties

In laminar flow, friction factor is predictable. In turbulent flow, it must be found from the Moody chart or equations such as Colebrook–White.
This calculator uses a user-supplied friction factor, allowing flexibility for different pipe materials, flow conditions, and fluids.

How This Calculator Works

This calculator estimates pressure drop through a pipe by:

  1. Asking for key parameters:
    friction factor, pipe length, diameter, fluid density, and velocity

  2. Applying the Darcy–Weisbach equation

  3. Computing and displaying the pressure drop instantly in Pascals (Pa)

The tool provides a fast and reliable way to evaluate pressure losses for pipe flow design—useful for engineers working in mechanical, chemical, process, HVAC, and fluid transport systems.