Make empty required fields impossible to miss. A rule that flags blank cells — optionally only when a related field is filled — turns a form into a self-checking checklist.
The example
Missing entries in a required column are flagged.
| A | B | |
|---|---|---|
| 1 | Name | |
| 2 | Ann | ann@x.com |
| 3 | Bo | (blank — flagged) |
The formula
Flag empty required cells:
How it works
An emptiness test drives the highlight:
=A2=""(or=ISBLANK(A2)) is TRUE for an empty cell.- Apply it to the required column so blanks light up — an instant “you missed this” cue.
- Make it conditional:
=AND($A2<>"", B2="")flags a missing email only when the row has a name (i.e. is actually in use). - Pair with Data Validation if you want to block submission, not just highlight gaps.
ISBLANK vs ="". ="" treats a formula returning an empty string as blank; ISBLANK does not (it’s only TRUE for truly empty cells). For form fields, =A2="" is usually the friendlier choice.
Try it: interactive demo
Rows “name,email”; missing email flagged when name present.
Variations
Plain blank flag
Any empty cell:
Required only if row used
Conditional:
Count missing
How many gaps:
Pitfalls & errors
Formula blanks. A cell with ="" looks empty but isn’t to ISBLANK. Use =A2="" to treat both as blank.
Spaces aren’t blank. A cell with just a space isn’t empty — test TRIM(A2)="" to catch those.
Highlight ≠ enforce. CF shows gaps; it can’t prevent saving. Add validation if a field must be filled.
Practice workbook
Frequently asked questions
How do I highlight empty required cells in Excel?
What is the difference between ISBLANK and =""?
Can conditional formatting prevent leaving a field blank?
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