What Is the ISBLANK Function?
ISBLANK checks whether a cell is completely empty and returns TRUE if it is, or FALSE if it contains anything at all. It is one of the simplest functions in Google Sheets, but it comes up constantly in data validation, conditional formatting, and error handling. If a cell contains a space, an empty string from a formula, or a zero-length value, ISBLANK will return FALSE, which catches many people off guard.
Syntax
=ISBLANK(cell)
| Parameter | Description |
|---|---|
| cell | The cell reference to check. This should be a single cell, not a range. |
The function returns TRUE only when the cell is genuinely empty with no content, no formula, and no invisible characters.
Basic Examples
Simple Empty Check
| A | B (Formula) | B (Result) | |
|---|---|---|---|
| 1 | Value | Is Blank? | Is Blank? |
| 2 | Hello | =ISBLANK(A2) | FALSE |
| 3 | =ISBLANK(A3) | TRUE | |
| 4 | 0 | =ISBLANK(A4) | FALSE |
Note that zero is not blank. A cell containing 0 is not empty.
Using ISBLANK with IF to Show Custom Messages
| A | B | C (Formula) | C (Result) | |
|---|---|---|---|---|
| 1 | Task | Due Date | Status | Status |
| 2 | Write report | 2026-04-10 | =IF(ISBLANK(B2),"No date set","Scheduled") | Scheduled |
| 3 | Review budget | =IF(ISBLANK(B3),"No date set","Scheduled") | No date set |
This is a clean way to handle missing data without showing errors or confusing blanks.
Counting Blank Cells in a Range
While ISBLANK works on a single cell, you can count blanks across a range with COUNTBLANK:
=COUNTBLANK(B2:B50)
Or, if you specifically want to count non-blank cells:
=COUNTA(B2:B50)
Advanced Examples
Preventing Calculations on Incomplete Rows
When you have a spreadsheet where users fill in data row by row, partial entries can produce misleading results. Wrapping your calculation in an ISBLANK check keeps things clean:
=IF(OR(ISBLANK(B2), ISBLANK(C2)), "", B2 * C2)
If either the quantity (B2) or the price (C2) is missing, the formula returns an empty string instead of zero or an error. This prevents half-filled rows from polluting your totals.
ISBLANK with Conditional Formatting
You cannot type ISBLANK directly into a conditional formatting dialog, but you can use the custom formula option. To highlight every row where the email column (D) is empty:
- Select the range you want to format (e.g., A2:F100).
- Go to Format > Conditional formatting.
- Choose "Custom formula is" and enter
=ISBLANK($D2). - Pick a fill color and click Done.
The dollar sign on $D locks the column while allowing the row to shift, so the rule applies correctly across all selected rows.
Difference Between ISBLANK and Comparing to Empty String
These two approaches look similar but behave differently:
=ISBLANK(A2) // TRUE only if A2 is truly empty
=A2="" // TRUE if A2 is empty OR contains an empty string from a formula
If cell A2 contains ="" (a formula that returns nothing), =ISBLANK(A2) returns FALSE, but =A2="" returns TRUE. Choose the one that fits your situation. When you need to catch formula-generated blanks, =A2="" is the safer bet.
Common Mistakes
- Assuming spaces are blank. A cell with one or more spaces looks empty but is not. ISBLANK returns FALSE. Use
=TRIM(A2)=""if you need to treat whitespace-only cells as blank. - Passing a range instead of a single cell.
=ISBLANK(A2:A10)will only evaluate the first cell in the range. To check multiple cells, use COUNTBLANK or wrap ISBLANK in ARRAYFORMULA. - Confusing ISBLANK with empty-string comparison. As noted above, a cell that contains
=""is not blank according to ISBLANK. Decide whether you care about truly empty cells or visually empty cells and pick the right approach.
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