Reynolds Number Calculator for Pipe Flow

This Reynolds Number (Re) calculator characterizes pipe flow as either laminar (Re<2300), turbulent (Re from 2300 to 3999), or transitional (Re>=4000). The Reynolds number is calculated based on pipe diameter, fluid speed, and material attributes.

The Reynolds number equation is represented as:

Re = (Velocity)*(Pipe Diameter)/(Kinematic Viscosity)

The Reynolds number helps predict flow patterns, which are used to determine significant operating conditions in mechanical equipment. Laminar flow provides a predictable flow profile. Transition flow means that at times the flow may be laminar, but also may switch to turbulent. When a flow is characterized as fully turbulent, eddy currents are generated across the entire fluid boundary. These eddy currents may in turn cause cavitation or other flow instabilities.

This Reynolds number calculator uses the most common fluids in industrial applications. If you would like to have an additional fluid added to the calculator, please contact us at

Flow Details
Reynolds Number
Flow Type

Disclaimer: fluid temperature has significant impact on temperature. A higher operating temperature is positively correlated to a higher Reynolds number.