Information
ISBLANK function: why formula "" cells return FALSE and how to test both
Distinguish genuinely untouched cells (ISBLANK = TRUE) from zero-length formula strings "" and spaces.
ISBLANK tests for zero cell contents—not visual emptiness
ISBLANK(value) returns TRUE only when a cell contains nothing at all—no value and no formula. If a cell holds a formula like ="" (a zero-length string) or a stray space " ", the cell looks blank on screen, yet ISBLANK returns FALSE!
When you want to catch both true blanks AND formula "" outputs without ever confusing numeric 0 with empty text, test COUNTBLANK(B3:B3)=1.
| Cell | Stored Content | ISBLANK | COUNTBLANK(cell)=1 |
|---|---|---|---|
| B2 (empty) | (truly empty) | TRUE | TRUE |
| B3 | ="" (formula empty string) | FALSE | TRUE |
| B4 | 0 (numeric zero) | FALSE | FALSE |
Compare ISBLANK on true empty B2 vs formula "" in B3
B2 is omitted/empty so ISBLANK(B2) is TRUE; B3 holds ="" so ISBLANK(B3) is FALSE while COUNTBLANK(B3:B3)=1 is TRUE.
=ISBLANK(B2)Type-safe blank-or-empty-string guard with COUNTBLANK
IF(COUNTBLANK(B4:B4)=1, "Missing", B4) flags both true blanks and ="" strings as "Missing" while keeping numeric 0 intact.
=IF(COUNTBLANK(B4:B4)=1, "Missing", B4)Try the example
Use the original values or change them to test your understanding.