Use the ISBLANK function

ISBLANK returns TRUE if a value refers to an empty cell, FALSE if there's data or a NULL value. Use ISBLANK with an =IF statement to return values or messages other than TRUE or FALSE. 

=ISBLANK (value)

Example 1: Uses =IF to replace a blank value with a zero, or return the actual cell value if not. =IF(ISBLANK(D15),0,D15)

Example 2: Uses =IF to prompt for input.
=IF(ISBLANK(D15),"Enter something",D15)

Tip: If you're checking for divide by zero or other errors, use IFERROR. For more info, see Use the IFERROR function.

ISBLANK returns TRUE if a value refers to an empty cell, FALSE if there's data or a NULL value. Use ISBLANK with an =IF statement to return values or messages other than TRUE or FALSE. 

=ISBLANK (value)

Example 1: Uses =IF to replace a blank value with a zero, or return the actual cell value if not. =IF(ISBLANK(D15),0,D15)

Example 2: Uses =IF to prompt for input.
=IF(ISBLANK(D15),"Enter something",D15)

Tip: If you're checking for divide by zero or other errors, use IFERROR. For more info, see Use the IFERROR function.

ISBLANK returns TRUE if a value refers to an empty cell, FALSE if there's data or a NULL value. Use ISBLANK with an =IF statement to return values or messages other than TRUE or FALSE. 

=ISBLANK (value)

Example 1: Uses =IF to replace a blank value with a zero, or return the actual cell value if not. =IF(ISBLANK(D15),0,D15)

Example 2: Uses =IF to prompt for input.
=IF(ISBLANK(D15),"Enter something",D15)

Tip: If you're checking for divide by zero or other errors, use IFERROR. For more info, see Use the IFERROR function.