Reynolds Number Calculator + Online Solver With Free Steps

The Online Reynolds Number Calculator is a free tool that helps you find the value of the Reynolds Number of a fluid.

Many parameters are involved in Reynolds Number: Density, Velocity, diameter, etc. So, the calculator takes the values of these parameters and, using the equation for the Reynolds number, returns the value of the Reynolds number.

reynolds number calculator

What Is the Reynolds Number Calculator?

Reynolds Number Calculator is an online calculator that is specifically designed to quickly find the value of the Reynolds Number of liquids to solve problems related to fluids.

Reynolds Number is a fundamental dimensionless quantity and fluid dynamics. It explains the type of flow of a liquid. Many real-life problems include finding the value of Reynolds Number to study the properties of liquids.

Such kind of real-life problem needs the value of the Reynolds Number to know about the flow of liquids. There is a general equation that is used, with some manipulations depending upon the cases, to find this number.

This tool is easily accessible if you have good internet connectivity and you are using a good browser. It is available 24/7 and you do not need any prior installation of the app, you just have to visit the website and work. It’s simple and user-friendly.

This is a very useful tool that helps physicists and science students to solve fast their complex problems. More detailed information about the working and usage of this calculator is given in the next section. Keep reading for further explanation.

How To Use the Reynolds Number Calculator?

You can use the Reynolds Number Calculator by putting the values of required quantities in the boxes provided. The calculator is very easy to understand due to its simple and clear display.

The calculator has four input boxes, you need to provide values in each of the provided boxes to get the proper result. One thing that you should always keep in mind is that you must match the units of quantities with the one mentioned in the box label.

If your root value is in some other dimension, you must convert it into the standard form before putting it in the calculator as input. Otherwise, you will not be able to get the proper results.

Once you have all the values in their standard form, you can put them in the given spaces and now you are ready to use the calculator.

To get the exact results from this calculator, a step-by-step guideline is provided below. You must follow these steps while using this calculator.

Step 1

Enter the mass density in the first box labeled as Density. You should write density in unit kg/m^3. In the next box enter the value of the volumetric flow rate. Its unit should be m^3/s.

Step 2

Insert the viscosity of the fluid in the third box labeled as Viscosity. The unit for viscosity in Pa*s. Now, enter the diameter in the last box. The unit of diameter is cm.

Step 3

To get the final solution, click on the Submit button.


The output of the calculator is a constant value. This constant will be the Reynolds Number for the respective fluid.

How Does the Reynolds Number Calculator Work?

The Reynolds Number Calculator works by finding the constant value of the Reynolds Number for the specific fluid. This calculator will be easy and better to use when there is knowledge about Reynolds Number and its related terms.

What Is Reynolds Number?

Reynolds Number is the ratio of inertial forces to viscous forces. It is a constant number without any dimension or unit. It gives information about the flow of fluid whether it will be laminar flow or turbulent flow.

Normally, if the value of the Reynolds Number is less than 2000, the flow is laminar and if its value is more than 2000 it is turbulent flow. It is not the hard and fast rule that a value more than 2000 will surely represent that the flow is turbulent.

Laminar and Turbulent Flow

Laminar flow is the smooth flow of fluid along a specific path. The fluid moves along clear streamlines that are straight and parallel as well. That is why this type of flow is also called streamline flow. Such flow usually occurs in small pipes.

The Turbulent Flow is the irregular or zigzag flow of fluid in a pipeline. It usually occurs when a fluid is flowing in the pipes with a greater diameter and the liquid is flowing at high velocity.

Fluid in Physics

Fluid in physics is an object that can flow and tends to fill the spaces in its surroundings. In physics, fluid is a material that cannot sustain a tangential shearing force when it is at rest position and continuously changes its shape when it’s under motion.

Equation for Reynolds Number

The Reynolds Number Calculator uses a standard equation of calculations. The equation is:

Re = ๐†๐ผโ„“/๐ถ


Re = Reynolds Number

๐† = Mass Density

๐ผ = Characteristic Speed

โ„“ = Characteristic Length

๐ถ = Dynamic Viscosity

The calculator finds the value of calculator speed by using the Volumetric Flow rate as:

V= ๐ผA

๐ผ = V/A


A= โ„ผr^2

All these values are put in the formula and the result is obtained.

Solved Example

Fluid has a viscosity of 1 Pa*s and its volumetric flow rate is 1m^3/s. The mass density is 1000kg/m^3 and the diameter of the pipe is 10 cm. Calculate the Reynolds Number for this fluid.


The input data to the calculator will be:

Density = 1000 kg/m^3

Volumetric Flow Rate = 1 m^3/s

Viscosity = 1 Pa*s

Diameter = 10 cm

The calculator will first calculate the velocity as:

๐ผ = V/A

=ย  V/โ„ผr^2

= 1/0.00785


Now, it uses the standard equation:

Re = ๐†๐ผโ„“/๐ถ

=(1000 kg/m^3*127.32 m/s*0.1m)รท1kg/m/s

Re =12732

So, Reynold’s Number for this fluid is 12732 which means it is a turbulent flow.

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