Free Reynolds Number Calculator
Calculate the Reynolds number for flow through a pipe or over a surface: Re = rho * v * L / mu, with laminar/turbulent classification.
kg/m3
m/s
m
Pa s
Reynolds Number
100,000.00
Kinematic Viscosity0.00000100 m2/s
Reynolds Number vs Fluid Density
Reynolds Number
The Reynolds number predicts whether flow will be laminar (smooth) or turbulent (chaotic).
Formula
Re = rho v L / mu
For pipe flow: Re < 2300 is laminar, 2300-4000 is transitional, > 4000 is turbulent.
Example Calculation
Water (rho = 1000, mu = 0.001) at 2 m/s through a 5 cm pipe.
- 01Re = rho v L / mu
- 02Re = 1000 * 2 * 0.05 / 0.001
- 03Re = 100 / 0.001 = 100 000
- 04This is well into the turbulent regime.
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