Enter the friction factor, pipe length, pipe diameter, fluid velocity, and fluid density into the calculator to determine the pressure loss.

Pressure Drop Formula

The following is the pressure drop formula used to calculate a pressure drop through pipe flow.

P = f * (L/D) * (p*V^2 / 2)

  • Where P is the pressure drop (pressure loss N/m^2)
  • f is the friction factor
  • L is the length of the pipe (m)
  • D is the pipe diameter (m)
  • V is the fluid velocity (m/s)
  • p is the fluid density (kg/m^3)

Pressure Drop Definition

A pressure drop is a change in pressure across a length of pipe that has fluid moving through it. The fluid flow causes a pressure differential across the length due to the forces of friction and flow.

How to calculate a pressure drop?

  1. First, determine the friction factor. This is known as the Darcy friction factor and is a combination of friction between the fluid and pipe and internal fluid friction.
  2. Next, measure the length of the pipe.
  3. Next, measure the diameter of the pipe.
  4. Next, determine the fluid velocity. This should be the average velocity of the fluid.
  5. Next, determine the fluid density. For water, this would be 997 kg/m^3.
  6. Finally, calculate the pressure drop.


What is static pressure loss?

A static pressure loss is a negative change in pressure that is not due to the flow of fluid.

What is a dynamic pressure loss?

A dynamic pressure loss arises from the frictional forces of fluid flow.

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