ReynoldsN · fluids

ReynoldsN reynolds number

Classify laminar vs transitional vs turbulent regime for a pipe-flow screening discussion

TECHNICAL UTILITY · REYNOLDS_NUMBER

Result

Enter values to begin.

Re = ρ·V·D / μ

How to use this estimate

Compute the Reynolds number Re=ρVD/μ from density, velocity, diameter, and dynamic viscosity. How it works: Re = ρ·V·D / μ. Out of scope: Moody chart f; entrance effects; non-Newtonian rheology; compressibility. Informational calculation for the stated inputs only. Does not certify code compliance; confirm manufacturer data where it applies.

Sources, methodology, and assumptions

Methodology

Re = ρ·V·D / μ

Assumptions

Newtonian fluid; Characteristic diameter as entered. Informational calculation for the stated inputs only.

Out of scope

Moody chart f; entrance effects; non-Newtonian rheology; compressibility

Sources

NIST SP 811 — unit consistency context (not exact formula page) — NIST
NIST fluid / viscosity unit context — NIST

Last technically reviewed: 2026-09-11