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

Practice

1. Which Tableau function converts a string like '123' into an integer?

easy

A. FLOAT()

B. STR()

C. DATE()

D. INT()

Solution

1. Step 1: Understand the input type

   The input is a string '123' which represents a number but is stored as text.

2. Step 2: Choose the function to convert string to integer

   INT() converts a string that looks like a number into an integer type.

3. Final Answer:

   INT() -> Option D

4. Quick Check:

   String '123' to number = INT() [OK]

Hint: Use INT() to convert numeric strings to whole numbers [OK]

Common Mistakes:

• Using STR() which converts numbers to strings
• Using DATE() which converts to date format
• Using FLOAT() when integer is needed

2. Which of the following is the correct syntax to convert a date string '2023-06-01' to a date in Tableau?

easy

A. FLOAT('2023-06-01')

B. DATE('2023-06-01')

C. INT('2023-06-01')

D. STR('2023-06-01')

Solution

1. Step 1: Identify the data type to convert to

   The string '2023-06-01' represents a date, so we want to convert it to a date type.

2. Step 2: Use the DATE() function for conversion

   DATE() converts a string formatted as a date into a Tableau date type.

3. Final Answer:

   DATE('2023-06-01') -> Option B

4. Quick Check:

   Convert date string to date = DATE() [OK]

Hint: Use DATE() to convert date strings to date type [OK]

Common Mistakes:

• Using STR() which converts to string, not date
• Using INT() or FLOAT() which cause errors on date strings
• Missing parentheses in function call

3. What is the result of this Tableau calculation?

INT('45.67')

medium

A. Error

B. 45

C. 46

D. 45.67

Solution

1. Step 1: Analyze the input string

   The string '45.67' represents a decimal number.

2. Step 2: Understand INT() behavior on decimal strings

   INT() expects a string representing an integer; passing a decimal string causes an error in Tableau.

3. Final Answer:

   Error -> Option A

4. Quick Check:

   INT('45.67') causes error [OK]

Hint: INT() only converts strings representing whole numbers [OK]

Common Mistakes:

• Expecting an error on decimal strings
• Thinking INT() rounds up to 46
• Confusing truncation with keeping decimals

4. You wrote this Tableau formula but get an error:

FLOAT('abc')

What is the likely cause?

medium

A. The string 'abc' cannot convert to a number

B. FLOAT() requires a date input

C. Missing quotation marks around abc

D. FLOAT() only works on integers

Solution

1. Step 1: Check the input string

   The string 'abc' contains letters, not numeric characters.

2. Step 2: Understand FLOAT() conversion rules

   FLOAT() converts strings representing numbers to decimal numbers; non-numeric strings cause errors.

3. Final Answer:

   The string 'abc' cannot convert to a number -> Option A

4. Quick Check:

   Non-numeric string to FLOAT() = Error [OK]

Hint: Only numeric strings convert with FLOAT() [OK]

Common Mistakes:

• Thinking FLOAT() works on any string
• Assuming FLOAT() needs date input
• Forgetting quotes around strings

5. You have a field [Sales] stored as string values like '1000', '2000', and '3000'. You want to calculate the average sales as a number. Which formula correctly converts and averages these values?

hard

A. INT(AVG([Sales]))

B. AVG(STR([Sales]))

C. AVG(INT([Sales]))

D. AVG(DATE([Sales]))

Solution

1. Step 1: Convert string sales to numbers before averaging

   Since [Sales] is string, convert each value to integer using INT() first.

2. Step 2: Apply AVG() on converted integers

   AVG(INT([Sales])) calculates the average of numeric sales correctly.

3. Final Answer:

   AVG(INT([Sales])) -> Option C

4. Quick Check:

   Convert then average = AVG(INT()) [OK]

Hint: Convert strings to numbers before aggregation [OK]

Common Mistakes:

• Averaging strings directly causes errors
• Converting after averaging strings is invalid
• Using DATE() on numeric strings