Moody Diagram & Friction Factor
The Moody diagram is a graph used to determine the Darcy friction factor for fluid flow in pipes. The friction factor depends on the Reynolds number and the relative roughness (ε/D) of the pipe material. Use the calculator below to find the relative roughness for your pipe material and diameter.
Moody Diagram
How to use: Find your relative roughness (ε/D) on the left axis and your Reynolds number (Re) on the bottom axis. The intersection point shows your friction factor on the right axis.