DAX Data Types

Choosing the right data type in DAX.

In DAX, every column and expression has a specific data type. Choosing the right data type is essential for accurate calculations, performance, and building effective models in Power BI, Excel Power Pivot, and SSAS Tabular.

Core DAX Data Types

Data TypeDescriptionExample
Whole Number (Integer)Stores whole numbers1, 25, -300
Decimal Number (Fixed Decimal / Currency)Fixed-point number with 4 decimal places of precision10.25, 1000.5678
Floating Point (Double)High-precision decimal numbers (less commonly used)3.14159, 1.797E+308
Boolean (TRUE/FALSE)Logical true/false valuesTRUE, FALSE
Text (String)Any combination of characters"Sales", "2025"
Date/TimeStores date and time values (stored as numbers behind the scenes)2025-08-31, 2025-08-31 15:30
Blank (Null)Represents missing or unknown valuesBLANK()

Notes on Numeric Types

  • DAX has implicit conversions, but it’s important to know the differences:

    • Whole Number → Best for counts, IDs
    • Decimal → Used for money, percentages
    • Floating Point → Rarely needed; can introduce rounding errors

Behavior of Data Types in DAX

  • DAX does not support custom data types like arrays, objects, or records.

  • BLANK() behaves like NULL but with special logic:

    • BLANK() + 5 = 5
    • BLANK() = 0 returns TRUE in some comparisons

  • Text and numbers are not always interchangeable (e.g., "5" ≠ 5).

Example: Data Type Conversion

Revenue as Text = FORMAT(Sales[Revenue], "Currency")

This converts a decimal number to a text value formatted as currency.

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