Calculated Fields in Tableau allow you to create new data from existing data in your dataset. These fields can be used to create custom metrics, filters, or new dimensions for deeper analysis. Calculated fields let you perform operations like arithmetic, logical conditions, string manipulations, and more.

How to Create a Calculated Field in Tableau:

1. Open Tableau and Load Your Data

• Open Tableau Desktop and load your data source (Excel, SQL, CSV, etc.).

2. Create a New Calculated Field

• In the Data pane on the left, right-click anywhere and select Create Calculated Field.
• The Create Calculated Field dialog box will appear.

3. Name the Calculated Field

• At the top of the dialog box, provide a name for the calculated field. Make it descriptive, so you know what it does (e.g., Profit Margin, Discounted Price, Year-over-Year Growth).

4. Write a Formula

• In the formula box, write the formula using available fields, functions, and operators. Tableau offers several categories of functions such as:
  • Mathematical Functions: +, -, *, /, etc.
  • Logical Functions: IF, THEN, ELSE, CASE, AND, OR.
  • String Functions: LEFT(), RIGHT(), LEN(), UPPER(), LOWER(), CONCAT().
  • Date Functions: DATEPART(), DATEDIFF(), NOW().
  • Aggregate Functions: SUM(), AVG(), MIN(), MAX().
  Example formulas:
• Profit Margin:
  sql [Profit] / [Sales]
• Discounted Price:
  sql [Sales] * (1 - [Discount])
• Year-over-Year Growth:
  sql ([Sales] - LOOKUP([Sales], -1)) / LOOKUP([Sales], -1)

5. Validate the Formula

• Tableau will automatically check the formula for syntax errors. If your formula is correct, a green checkmark will appear. If there’s an error, a red exclamation mark will appear, and you will need to correct the formula.

6. Click OK

• Once the formula is valid, click OK. The calculated field will now appear in the Data pane under Dimensions or Measures based on its type.

Types of Calculated Fields:

1. Basic Arithmetic Calculations:

• Example: Calculating the Profit Margin:
  sql [Profit] / [Sales]

1. String Manipulations:

• Example: Creating a new customer label:
  sql IF [Customer Type] = 'VIP' THEN "Premium Customer" ELSE "Standard Customer" END

1. Date Calculations:

• Example: Calculating the Number of Days Between Two Dates:
  sql DATEDIFF('day', [Order Date], [Ship Date])

1. Conditional Logic:

• Example: Applying IF-THEN Logic:
  sql IF [Sales] > 10000 THEN "High Sales" ELSE "Low Sales" END

1. Aggregations:

• Example: Calculating the Average Sales:
  sql AVG([Sales])

Using Calculated Fields in Visualizations:

• After creating a calculated field, you can drag it into your view just like any other field.
• You can place it on Rows, Columns, Filters, Color, Size, etc., to dynamically modify your visualizations.

Example Use Cases:

1. Profit Margin Calculation:
   To analyze the profitability of products or regions, you can create a calculated field like:

   [Profit] / [Sales]

This will help visualize the profit margins across different categories.

2. Custom Binning:
   If you want to group continuous values into categories, you can create a calculated field with conditional logic, such as:

   IF [Sales] < 1000 THEN 'Low'
   ELSEIF [Sales] < 5000 THEN 'Medium'
   ELSE 'High' END

3. Combining Strings:
   You can combine text fields for custom labels or names:

   [First Name] + ' ' + [Last Name]

Conclusion:

Calculated fields are a powerful feature in Tableau that enable you to customize and extend your data analysis. You can create new metrics, apply conditional logic, manipulate strings, or perform advanced date and aggregation calculations.