DAX function

IF — DAX function reference

Branch on a condition.

Syntax

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IF(<logical_test>, <value_if_true>, [<value_if_false>])

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IF([Sales] > 0, "Yes", "No")

→ One of two values

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IF(SUM(Sales[Amount]) > [Target], "Above target", "Below target")

→ A status label measure

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IF(ISBLANK([Total Sales]), BLANK(), IF([Total Sales] > 100000, "High", "Low"))

→ Nested IF — SWITCH(TRUE()) is usually cleaner past two levels

Omitting value_if_false makes IF return BLANK() when the condition is false — fine for measures (blanks are hidden in most visuals) but can surprise you in a calculated column, where you’ll see a literal blank cell.
IF tries to keep a consistent data type across both branches; mixing types (a number and a string) triggers implicit conversion to text — keep both branches the same type to avoid unexpected formatting.

From Logical & error handling