How to Use SWITCH and VAR to Make Your DAX Measures More Readable and Efficient in Power BI

Building efficient DAX measures is essential to make sure your reports perform well. Two good practices help a lot here: using VAR and using SWITCH, each with a different role.

SWITCH is used to simplify conditional expressions that need to return different values based on several conditions.

Consider the following DAX measure, which evaluates the performance of a measure called [Variance]:

Variance KPI = IF([Variance] > 0.80, "Amazing!", IF([Variance] > 0.60, "Good", "Bad"))

Although it works correctly, you can notice that there are a few nested IFs and that the [Variance] measure is called more than once in this expression.

This increases unnecessary processing, especially in models with large volumes of data. This formula can be more efficient — and more readable too.

The solution with SWITCH and VAR

Restructuring the measure with SWITCH(TRUE()) and an intermediate variable, we get the optimized version:

VAR Calc = [Variance]

RETURN
SWITCH
(
    TRUE(),
    Calc > 0.80, "Amazing!",
    Calc > 0.60, "Good",
    "Bad"
)

The Calc variable stores the value of [Variance] only once, which removes the need for further calls to this measure.

Each feature has its own role:

• VAR → performance: the value is calculated once and reused. This is where the performance gain comes from.
• SWITCH(TRUE()) → readability: on its own, SWITCH is not faster than nested IFs. What it brings is cleaner code: the conditions are lined up, in the order they are evaluated, and are easy to read, understand and maintain in the future.

One more example: classifying target attainment

Here is a measure that classifies sales results against a target. In the version with nested IFs, both [Total Sales] and [Target] are called several times, and the logic is buried inside parentheses:

Goal Status =
IF([Total Sales] >= [Target] * 1.2, "Exceeded",
    IF([Total Sales] >= [Target], "Met",
        IF([Total Sales] >= [Target] * 0.8, "Almost there", "Below")))

Rewriting it with VAR and SWITCH(TRUE()):

Goal Status =
VAR CurrentSales = [Total Sales]
VAR CurrentTarget = [Target]
RETURN
SWITCH(
    TRUE(),
    CurrentSales >= CurrentTarget * 1.2, "Exceeded",
    CurrentSales >= CurrentTarget, "Met",
    CurrentSales >= CurrentTarget * 0.8, "Almost there",
    "Below"
)

What changed:

• Performance (VAR): each measure is calculated once, instead of three calls to [Total Sales] and three to [Target] in the previous version.
• Readability (SWITCH): the four bands appear one under the other, and changing a rule means editing a single line.
• Order matters: SWITCH(TRUE()) returns the result of the first true condition, so the bands must go from the most restrictive to the broadest (from >= CurrentTarget * 1.2 down to >= CurrentTarget * 0.8).

Best practices with SWITCH and variables in DAX

• Prioritize using variables: Whenever possible, store values in variables to avoid repeated calculations. This is where the performance gain comes from.
• Replace multiple IFs with SWITCH(TRUE()): This makes the code more readable, organized and easier to maintain.
• Test your measures: In large models, simple changes can bring significant efficiency gains. Compare before and after with the Performance Analyzer in Power BI Desktop.

📚 This article was based on a question from the Microsoft practice assessment for the DP-600 exam.