How to Use VAR and RETURN in DAX in Power BI

In DAX, VAR lets you store a value or expression result in a variable, and RETURN outputs the final result using those variables. This helps make formulas easier to read and improves performance by avoiding repeated calculations.

Syntax

The basic syntax of using VAR and RETURN in DAX is:

• VAR: Defines a variable and assigns it a value or expression.
• RETURN: Specifies the expression that uses the variables and produces the final result.

You can define multiple VAR variables before the RETURN statement.

DAX

MeasureName =
VAR VariableName = Expression
RETURN
    ResultExpressionUsingVariableName

Example

This example calculates the percentage of total sales for each product category using VAR to store intermediate values and RETURN to output the final percentage.

DAX

Category Sales % =
VAR TotalSales = SUM(Sales[Amount])
VAR OverallSales = CALCULATE(SUM(Sales[Amount]), ALL(Sales[Category]))
RETURN
    DIVIDE(TotalSales, OverallSales, 0)

Output

For a category with sales 5000 and overall sales 20000, output is 0.25 (25%)

Common Pitfalls

Common mistakes when using VAR and RETURN include:

• Not using RETURN after VAR declarations, which causes syntax errors.
• Trying to use variables outside the RETURN statement.
• Defining variables with complex expressions but not reusing them, missing performance benefits.

Always remember RETURN is required to output the final result.

DAX

WrongMeasure =
VAR Total = SUM(Sales[Amount])
// Missing RETURN causes error

CorrectMeasure =
VAR Total = SUM(Sales[Amount])
RETURN
    Total

Quick Reference

Keyword	Purpose	Notes
VAR	Defines a variable to store a value or expression	Can define multiple variables before RETURN
RETURN	Outputs the final result using variables	Must be used after VAR declarations
Variables	Hold intermediate results	Improve readability and performance
Scope	Variables exist only within the measure or calculated column	Cannot be accessed outside

Key Takeaways

Use VAR to store intermediate calculations and RETURN to output the final result in DAX.

Always include RETURN after VAR declarations to avoid syntax errors.

Variables improve formula readability and can boost performance by avoiding repeated calculations.

You can define multiple VAR variables before RETURN in a single measure.

Variables are local to the measure and cannot be used outside their scope.