Enter the Reynolds number into the calculator to determine the Darcy Friction Factor. This calculator can also evaluate any of the variables given the others are known.

Darcy Friction Factor Formula

The following formula is used to calculate the Darcy Friction Factor.

f = 0.0791 / (Re)^{0.25}


  • f is the Darcy Friction Factor (dimensionless)
  • Re is the Reynolds number (dimensionless)

To calculate the Darcy Friction Factor, divide 0.0791 by the Reynolds number raised to the power of 0.25.

What is a Darcy Friction Factor?

The Darcy Friction Factor, also known as the Darcy-Weisbach friction factor, is a dimensionless quantity used in fluid dynamics to represent the resistance to flow in a pipe. It is a key parameter in the Darcy-Weisbach equation, which relates the head loss, or pressure loss, due to friction along a given length of pipe to the average velocity of the fluid flow. The factor depends on the roughness of the pipe’s interior surface and the Reynolds number, a measure of the flow’s turbulence.

How to Calculate Darcy Friction Factor?

The following steps outline how to calculate the Darcy Friction Factor.

  1. First, determine the Reynolds number (Re) value.
  2. Next, substitute the Reynolds number value into the formula: f = 0.0791 / (Re)^0.25.
  3. Finally, calculate the Darcy Friction Factor (f).
  4. After inserting the Reynolds number value and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Reynolds number (Re) = 5000