Reynolds Number Calculator
Determine laminar vs turbulent regime using Re = ρ V L / μ.
How to Use This Calculator
1
Provide fluid properties
Enter density ρ and dynamic viscosity μ.
2
Enter velocity and length
Use characteristic length (e.g., pipe diameter).
3
Calculate Re
Interpret the regime from the result.
Formula
Re = ρ · V · L / μ
Where: Re is Reynolds number, ρ density, V velocity, L length, μ dynamic viscosity.
Example: ρ=1000, V=2.5, L=0.05, μ=0.001 ⇒ Re=125,000 (turbulent).
Frequently Asked Questions
Which L should I use?
For internal flow, use hydraulic diameter (pipe diameter for circular pipes). For external flow, use chord length or characteristic size.
Dynamic vs kinematic viscosity?
Dynamic μ (Pa·s). Kinematic ν = μ/ρ (m²/s). You can compute μ = ν·ρ if ν is known.