Flow Parameters
Fluid Parameters

Reynolds Number Calculator

The Reynolds number is defined as the proportion of fictitious force to liquid forces.

In other words, A dimensionless amount employed to classify the fluids systems is known as the Reynolds number. The influence of viscosity is necessary for constraining the velocities or the flow pattern of a liquid or fluid.


Formula of Reynolds Number Calculator

In mathematical form, the Reynolds number (NRe) is expressed as:

\[{N_{{\mathop{\rm Re}\nolimits} }} = \frac{{\rho vd}}{\mu }\]


ρ = density of the fluid.

v = velocity of the fluid.

d = diameter of fluid.

μ = diameter of the fluid.


To gain knowledge about density, click the Density Calculator.

History of Reynolds Number Calculator

The word Reynolds number is taken from the British physicist named Osborne Reynolds. He found this while examining various fluid flow components like the flow of liquor from a pipe and an airplane wing's movement by air.

He also noted that the nature of flow could transition from laminar to turbulent wholly quickly.

Where can the Reynolds number be used?

The Reynolds number has extensive use in actual life. It can find the liquid flow in a pipe, flow nearby airfoils, or a thing driving in a liquid.


For a better understanding, let’s have a look at the example below:

Suppose we have to find Reynolds number, if a fluid contain viscosity = 0.4 Ns/m2 and comparative density = 900 Kg/m2 from a pipe having diameter = 20 mm with a velocity = 2.5 m.

Given data

Viscosity = μ = 0.4 Ns/m2
Density = ρ = 900 Kg/m2
Diameter = d = 20×10-3 m

To Find

Reynolds number = ?


NRe = ρvd / μ

Putting values in the above equation

NRe = (900)(2.5)(20 * 10-3) / 0.4
NRe = 112.5

From the answer solved above, we notice that the Reynolds number is lower than in 2000. So, according to the rule, the flow of liquor is laminar.

How to use Reynolds Number Calculator?

The steps to use the Reynolds number calculator are as follows:

Step 1: Enter the value of fluid velocity in the required input.

Step 2: Enter the value of the characteristic linear dimension in the required input.

Step 3: Enter the value of fluid density in the third required input.

Step 4: Enter the value of dynamic viscosity in the third required input.

Step 5: The calculator will automatically display an answer on the screen.

Calculator use

To immediately find the Reynolds number of liquor or air, you can use this calculator by putting the values in the prescribed answer that will be given to you on the screen. This free online calculator s made for you to solve complex problems in seconds.