Type conversion functions in Tableau - Step-by-Step Guide

Introduction

Type conversion functions in Tableau help you change data from one type to another. This is useful when your data is not in the right format for calculations or visualizations.

When your date is stored as text and you want to use it in a timeline chart

When numbers are stored as text and you want to perform math operations on them

When you want to convert a number to text to combine it with other text fields

When you need to change a string to a date to filter data by date ranges

When you want to ensure data types match for joining tables

Steps

Step 1: Open your Tableau workbook

- Data pane

You see your data fields listed

💡 Make sure your data source is connected and loaded

Step 2: Click the drop-down arrow next to a field you want to convert

- Data pane

A menu appears with options for the field

💡 Choose a field that needs type conversion, like a string date

Step 3: Select 'Create Calculated Field'

- Field drop-down menu

A calculation editor window opens

💡 This is where you write your type conversion formula

Step 4: Type the conversion function, for example: DATE([YourField])

- Calculation editor

The field will convert text to date format

💡 Use INT() to convert to integer, STR() to convert to string, FLOAT() for decimal numbers

Step 5: Click OK to save the calculated field

- Calculation editor

The new converted field appears in the Data pane

💡 Use this new field in your visualizations

Before vs After

Before

Field 'Order Date' is stored as text like '2023-06-01', calculations on dates fail

After

New calculated field 'Order Date (Date)' converts text to date format, allowing date filters and charts

Settings Reference

DATE()

📍 Calculation editor

Convert text or numbers to date format

Default: N/A

INT()

📍 Calculation editor

Convert values to whole numbers

Default: N/A

FLOAT()

📍 Calculation editor

Convert values to decimal numbers

Default: N/A

STR()

📍 Calculation editor

Convert values to text format

Default: N/A

Common Mistakes

Using DATE() on a string that is not in a recognizable date format

Tableau cannot convert invalid date strings and returns null

Ensure the string matches a date format like 'YYYY-MM-DD' before using DATE()

Trying to convert text with letters to INT() or FLOAT()

Non-numeric text cannot convert to numbers and causes errors

Clean or filter data to remove non-numeric text before conversion

Summary

Type conversion functions change data types to make data usable in calculations and visuals

Common functions include DATE(), INT(), FLOAT(), and STR()

Always check your data format before converting to avoid errors