About the Reynolds Number Calculator
Reynolds number for pipe flow and whether the flow is laminar, transitional or turbulent.
Also known as: re number, laminar or turbulent, reynolds formula.
How to use this calculator
- Enter fluid density, velocity, pipe diameter, dynamic viscosity.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
Re = ρvD / μ
Worked example
Using the values pre-filled in the calculator above:
- Fluid density = 1,000 kg/m³
- Velocity = 1.5 m/s
- Pipe diameter = 0.05 m
- Dynamic viscosity = 0.001 Pa·s
the calculator returns:
- Reynolds number: 75,000
- Flow regime: Turbulent
- Kinematic viscosity: 0.000001 m²/s