ISBLANK vs an Empty String in Excel and Google Sheets

A cell can look empty and still fail ISBLANK. I have wasted time on IF(ISBLANK(A2),"please fill this in",…) only to find A2 held a formula that returned "". It looks the same. It is not the same.

I checked four ordinary values, plus a cell I had never touched (Z99).

The unused cell is the only one ISBLANK accepted. Microsoft’s IS functions page is blunt about this: ISBLANK is TRUE when the argument is a reference to an empty cell, otherwise FALSE. A formula that returns empty text is not an empty cell. In this file ISBLANK of ="" was FALSE, ISTEXT was TRUE, and LEN was 0.

Z99="" was also TRUE. So IF(A2="") treats a never-used cell and a formula-empty cell as the same thing. That is often what I want on a form: “nothing useful is here.” IF(ISBLANK(A2)) is the narrower test: “nobody has written a formula or a value into this cell.” Microsoft’s page on using IF to check for a blank shows both patterns; pick the one that matches the data, not the one whose name sounds right.

A space is not empty under either test. LEN was 1. If a paste put " " into a column, both ISBLANK and ="" will say the cell is occupied. Trim first if that is a real risk.

The number 0 is also occupied. ISBLANK was FALSE, 0="" was FALSE, LEN was 1, and ISTEXT was FALSE. Do not use a blank check to look for zeros.

Counting the two kinds of “empty”

I ran COUNTBLANK and COUNTA on B2:B6, a five-cell mix that included two empty strings (one from ="", one I had stored as empty text), a space, the text 001, and the number 0:

=COUNTBLANK(B2:B6)    → 2
=COUNTA(B2:B6)        → 5

Then the unused cell by itself:

=COUNTBLANK(Z99)      → 1
=COUNTA(Z99)          → 0
=IF(ISBLANK(Z99),"blank","not")    → blank
=IF(Z99="","empty","not")          → empty

COUNTBLANK counted both empty strings in B2:B6, and it did not count the 0. That is exactly what Microsoft’s COUNTBLANK page says: formulas that return "" are counted, zeros are not. COUNTA goes the other way: it counts a formula that returns empty text, and it does not count a truly empty cell. COUNTA(Z99) was 0; COUNTA of the five-cell mix was 5, so the empty strings were included.

If you are trying to count “rows someone still has to fill,” COUNTA will treat a helper formula that returns "" as filled. COUNTBLANK or IF(A2="") will treat it as empty. I would use ISBLANK only when I specifically care that the cell has never been written to.

One practical note from the test itself: writing an empty string into a cell through an API left ISBLANK FALSE, ISTEXT TRUE, and LEN 0 — the same profile as ="". A cell that looks blank in the grid is not always an empty cell. I used Z99, which I had never written to, as the genuine blank.

This is a different problem from a #VALUE! on a function that will not accept a blank, or from IFERROR hiding a miss. Those are in VALUE error and IFERROR vs IFNA. And a stored "" can also show up as its own “unique” value in a list; see Unique Values.