In Power BI, you can create a custom or calculated table from the existing table. This article shows you how to create calculated tables with an example.
To demonstrate these Power BI Calculated Tables, we will use the SQL Data Source we created in Connect to SQL Server article. So, please refer to the same.

How to Create Calculated Tables in Power BI
In order to add the calculated table, please click on the New Table option under the Modeling tab.

It will open the Power BI DAX formula bar to write the DAX expression, as shown in the screenshot below.

Let me rename the default table name as Countries

For this Calculated Tables demo purpose, we select Countries from the DimGeography table. As you can see from the screenshot below, Power BI IntelliSense is showing the suggestions while I was typing.

From the screenshot below, you can see that we are selecting the DISTINCT (non-duplicates or unique) countries’ names from the Countries column.

By clicking the enter or any key for that matter will create a new table called Countries holding distinct country names.

Let me create a Map using that calculated table that we created earlier.
