Reynolds Number Calculator
Calculate Reynolds number for pipe flow from average velocity, pipe inner diameter, and either density with dynamic viscosity or kinematic viscosity.
Need velocity or pipe diameter first? Use the Pipe Velocity and Diameter Calculator.
Calculation Result
Enter pipe flow conditions and press Calculate to see Reynolds number.
Formula and Guideline
Re = rho u D / mu or Re = u D / nu
- Re: Reynolds number
- rho: density
- u: average velocity
- D: pipe inner diameter
- mu: dynamic viscosity
- nu: kinematic viscosity
The laminar, transitional, and turbulent ranges are general pipe-flow guidelines. Actual flow behavior can differ depending on pipe roughness, inlet conditions, fluid properties, and operating conditions.