Reynolds Number Calculator

Calculate Reynolds number, flow regime classification, and entrance length for internal pipe flow and external flow.

Average fluid velocity.
m/s
Pipe inner diameter or object dimension.
mm
Water@20°C: 998, Air@20°C: 1.2 kg/m³.
kg/m³
Water@20°C: 0.001, Air@20°C: 1.8e-5 Pa·s.
Pa·s

Results

Reynolds Number-
Flow Regime-
Entrance Length-mm
References: Munson — Fundamentals of Fluid Mechanics; ASME PTC 19.5