Home / Tools / Reynolds number

Reynolds Number Calculator

Re = ρ·v·D / μ. Tells you whether flow in a pipe is smooth (laminar) or chaotic (turbulent).

Fluid and flow

Calculates as you type

Fluid preset

Density, ρ

Unit

Viscosity, μ

Unit

Velocity, v

Unit

Pipe inside diameter, D

Unit

Reynolds number =

Pipe flow is usually treated as laminar below Re ≈ 2,300, turbulent above ≈ 4,000, and transitional in between.
Preset fluid properties are typical values at the stated temperature. Enter your own for other conditions.
Don't know the velocity? Use the pipe velocity calculator first.

Get in touch with ONB Engineering to talk it through.