How does the ISBLANK Function (DAX) work?

ISBLANK Function (DAX) checks if the value is null, and returns either TRUE or FALSE.

ISBLANK Formula Syntax

ISBLANK (<value>)

How do you use the ISBLANK function?

ISBLANK returns true whenever its only argument is a blank expression.

Considerations when using the ISBLANK function

When you use BLANK in a comparison, the conversion to 0 or to an empty string results in a positive match with these values. For this reason, comparing an expression to blank requires a specific function, ISBLANK, which returns true whenever its only argument is a blank expression.

Formula examples using the ISBLANK function

//Sales to Previous Year Ratio  
  
=IF( ISBLANK('CalculatedMeasures'[PreviousYearTotalSales])  
   , BLANK()  
   , ( 'CalculatedMeasures'[Total Sales]-'CalculatedMeasures'[PreviousYearTotalSales] )  
      /'CalculatedMeasures'[PreviousYearTotalSales])