Reynolds Number Calculator

Find the Reynolds number to classify flow.

Fluid density (kg/m³)

Velocity

Characteristic length

Dynamic viscosity (Pa·s)

Reynolds number 100,000

Formula: Re = ρ·v·L ÷ μ

Step-by-step with your numbers:

1. Values used:

2. Fluid density = 1,000 kg/m³

3. Velocity = 2

4. Characteristic length = 0.05

5. Dynamic viscosity = 0.001 Pa·s

7. Reynolds number = 100,000

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The Reynolds number predicts whether flow is laminar or turbulent.

The math behind it

Re = density × velocity × length ÷ viscosity. In pipes, <2300 is laminar, >4000 turbulent.

Water, 2 m/s, 0.05 m, 0.001 Pa·s → Re = 100,000 (turbulent).

Characteristic length?

For a pipe it's the diameter.