How to use the reynolds number calculator
Determine whether pipe flow is laminar or turbulent. Enter density, velocity, pipe diameter, viscosity in the fields above; the reynolds number, flow regime (2300 / 4000 limits) are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- rho — Density (kg/m³)
- v — Velocity (m/s)
- D — Pipe diameter (m)
- mu — Viscosity (Pa·s)
Worked example
With density = 1000 kg/m³, velocity = 1.5 m/s, pipe diameter = 0.05 m, viscosity = 0.001 Pa·s, the calculator gives reynolds number ≈ 75,000; flow regime (2300 / 4000 limits) ≈ Turbulent.
Frequently asked questions
What is the formula for the reynolds number calculation?
Reynolds number = rho × v × D / mu. Flow regime (2300 / 4000 limits) = [Reynolds number]<2300?"Laminar":([Reynolds number]<4000?"Transitional":"Turbulent"). Here rho is density (kg/m³), v is velocity (m/s), D is pipe diameter (m), mu is viscosity (Pa·s).
What inputs do I need for the reynolds number calculator?
You need density in kg/m³, velocity in m/s, pipe diameter in m, viscosity in Pa·s. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.