The image above represents dimensionless radius.

To compute for the dimensionless radius, two essential parameters are needed and these parameters are **external radius (r _{e}) and well radius (r_{w}).**

The formula for calculating the dimensionless radius:

r_{D} = ^{re} / _{rw}

Where;

r_{D} = Dimensionless Radius

r_{e} = External Radius

r_{w} = Well Radius

Let’s solve an example;

Given that the external radius is 18 and the well radius is 16.

Find the dimensionless radius?

This implies that;

r_{e} = External Radius = 18

r_{w} = Well Radius = 16

r_{D} = ^{re} / _{rw}

r_{D} = ^{18} / _{16}

r_{D} = 1.125

Therefore, the **dimensionless radius **is **1.125.**

**Calculating for the External Radius when the Dimensionless Radius and the Well Radius is Given.**

r_{e} = r_{D} x r_{w}

Where;

r_{e} = External Radius

r_{D} = Dimensionless Radius

r_{w} = Well Radius

Let’s solve an example;

Given that the dimensionless radius is 9 and the well radius is 20.

Find the external radius?

This implies that;

r_{D} = Dimensionless Radius = 9

r_{w} = Well Radius = 20

r_{e} = r_{D} x r_{w}

r_{e} = 9 x 20

r_{e} = 180

Therefore, the **external radius **is **180.**

**Calculating for the Well Radius when the Dimensionless Radius and the External Radius.**

r_{w} = ^{re} / _{rD}

Where;

r_{w} = Well Radius

r_{D} = Dimensionless Radius

r_{e} = External Radius

Let’s solve an example;

Given that the dimensionless radius is 10 and the external radius is 90.

Find the well radius?

This implies that;

r_{D} = Dimensionless Radius = 10

r_{e} = External Radius = 90

r_{w} = ^{re} / _{rD}

r_{w} = ^{90} / _{10}

r_{w} = 9

Therefore, the **well radius **is **9.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the dimensionless radius.

To get the answer and workings of the dimensionless radius using the **Nickzom Calculator – The Calculator Encyclopedia. **First, you need to obtain the app.

You can get this app via any of these means:

**Web** – https://www.nickzom.org/calculator-plus

To get access to the **professional **version via web, you need to **register** and **subscribe **for** NGN 1,500 **per** annum** to have utter access to all functionalities.

You can also try the **demo **version via https://www.nickzom.org/calculator

**Android (Paid)** – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator

**Android (Free)** – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

**Apple (Paid)** – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8

Once, you have obtained the calculator encyclopedia app, proceed to the **Calculator Map, **then click on **Petroleum **under **Engineering**

Now, Click on **Well Testing**** **under **Petroleum**

Now, Click on **Dimensionless Radius**** **under **Well Testing**

The screenshot below displays the page or activity to enter your values, to get the answer for the dimensionless radius according to the respective parameters which are the **external radius (r _{e}) and well radius (r_{w}).**

Now, enter the values appropriately and accordingly for the parameters as required by the **external radius (r _{e})** is

**18**and

**well radius (r**is

_{w})**16**.

Finally, Click on Calculate

As you can see from the screenshot above, **Nickzom Calculator**– The Calculator Encyclopedia solves for the dimensionless radius and presents the formula, workings and steps too.