ISBLANK vs ="" in Excel: Which Test for Empty

The short answer to ISBLANK vs empty string: ISBLANK(A2) is TRUE only when a cell is truly empty, while A2="" is TRUE when a cell is empty or holds an empty string, such as a formula that returns "". Because many cells that look empty actually contain formulas, A2="" is the safer everyday test. This comparison is for anyone whose blank check works on some rows and fails on others.

ISBLANK vs ="" at a glance#

ISBLANK checks whether a cell has any content; ="" checks whether its value is empty text.

An empty string is text with no characters, written as two double quotes with nothing between them: "". Formulas return it to leave a cell looking blank.

How ISBLANK works#

ISBLANK is one of Excel's IS functions. It takes one value and returns TRUE or FALSE.

=ISBLANK(A2)

It returns TRUE only when A2 has nothing in it: no number, no text, no formula. The moment the cell holds a formula, ISBLANK returns FALSE, even when that formula displays nothing. That is the source of most confusion.

The IS family also includes ISNUMBER, ISTEXT and ISERROR, which test what kind of value a cell holds. The ISNUMBER function guide shows a useful alternative: if a cell should hold a date or amount, =ISNUMBER(A2) is TRUE only when a real number is there, which rules out blanks, empty strings, spaces and text in one go. The overview of Excel's IS functions covers the rest of the family.

How the ="" test works#

A2="" is a comparison. It asks: "is the value of A2 equal to empty text?" and returns TRUE or FALSE.

=A2=""
=IF(A2="","Missing","Received")

For a truly empty cell, Excel treats the value as empty when compared with text, so the result is TRUE. For a formula that returns "", the value is empty text, so the result is also TRUE. In practice, ="" answers the question people usually mean: "does this cell show anything?"

The opposite test is A2<>"", which reads "A2 is not empty". It is the usual way to write "only if something has been entered" inside IF, COUNTIFS or FILTER.

The same cells tested both ways#

Here are five cells that might all look "empty-ish":

Row 2 is the key difference. A formula that returns "" looks empty, but ISBLANK says it isn't. Row 3 catches both tests: a space is a character, so the cell isn't empty. Wrapping the cell in TRIM, which removes extra spaces, treats it as empty.

A status column built both ways#

Suppose column B holds a paid date, and column C should say "Missing" or "Received".

=IF(ISBLANK(B3),"Missing","Received")
=IF(B3="","Missing","Received")

If B3 is truly empty, both return Missing. Now suppose column B is filled by a lookup that returns "" when nothing is found. The ISBLANK version now says Received for every unpaid invoice, while the ="" version still says Missing. Nothing on screen warns you that the first formula has broken.

Counting empty cells on the same data#

The same split shows up when you count. Say B2:B6 holds two paid dates, one truly empty cell and two lookup formulas that return "".

=COUNTBLANK(B2:B6)
=COUNTA(B2:B6)
=SUMPRODUCT(--ISBLANK(B2:B6))

COUNTBLANK returns 3, because it counts the empty cell and both empty strings, just like the ="" test. COUNTA returns 4, because it counts every cell with content, including the two formulas. The SUMPRODUCT version counts cells where ISBLANK is TRUE and returns 1. Three formulas, three answers, all "correct" for the question they ask. Decide which question you mean before you build a report on it.

When to use ISBLANK#

Use ISBLANK when you need to know that a cell has no content at all. It fits:

• Data-entry checks, where a person must type a value and a formula in the cell would itself be a problem.
• Finding cells to fill, such as gaps under a heading in an exported report. The guide to filling blank cells uses Go To Special > Blanks, which selects truly empty cells, the same ones ISBLANK sees.
• Auditing a sheet, to spot cells that contain formulas even though they look empty.
• Conditional formatting that highlights cells someone forgot to fill in, where the column has no formulas.

When to use =""#

Use ="" for most everyday checks of whether a cell shows a value. It fits:

• Columns filled by formulas, such as lookups or IF formulas that return "" when there is nothing to show.
• Status and flag columns, like "Missing" or "Done".
• Filtering and counting, such as the FILTER condition B2:B20<>"" or =SUMPRODUCT(--(B2:B20<>"")) to count cells that show a value.
• Data pasted as values from formulas, which can leave empty-string cells that ISBLANK doesn't treat as empty.

If spaces might sneak in, use TRIM(A2)="". If the cell should hold a number, ISNUMBER(A2) is stricter still.

Common mistakes when testing for empty cells#

1. Using ISBLANK on formula results. A formula returning "" is never blank to ISBLANK. Use ="".
2. Forgetting about spaces. A space looks empty but isn't. Clean the data with TRIM, or test TRIM(A2)="".
3. Testing with =0. =A2=0 returns TRUE for an empty cell, so blanks get counted as zeros. Test for empty first: =IF(A2="","",A2*2).
4. Mixing COUNTA and COUNTBLANK. COUNTA counts "" formula cells as filled, while COUNTBLANK counts them as blank. On the same range, the two can add up to more than the number of cells.
5. Writing " " instead of "". =A2=" " tests for a single space, not empty. The two quotes must touch.
6. Expecting a lookup to return blank. A lookup that hits an empty cell returns 0, not an empty value. Add &"" to the end, or wrap it in IF, to show an empty string instead.

When you have more than two outcomes to return, SWITCH can replace a chain of IF tests; see the SWITCH function and CHOOSE vs SWITCH.

Our recommendation#

Use A2="" as your default test for "is this cell empty?", and A2<>"" for "has something been entered?". It treats truly empty cells and empty-string formulas the same way, which matches what you see on screen. Reach for ISBLANK only when you specifically need to know that a cell has no content at all, such as when auditing formulas or checking typed input. Add TRIM when spaces might be present, and use ISNUMBER when the cell must hold a number.

In short: ="" for what you see, ISBLANK for what is really there.

Practise it#

Try the exercise on this page: build a status column with the ="" test. Then practise the IS functions and SWITCH in a live spreadsheet: you type each formula, and it checks your answer instantly.