Empty cells that show nothing of their own
Safe. On by default.
Removes empty cells with no value, formula or formatting of their own.
Why it takes space
A worksheet stores a record for each cell it holds, and a record can exist with no value, formula or text in it. Formatting a whole column, clearing cells with Delete instead of Clear All, and code libraries that write a record for every position all leave empty records behind, sometimes a million rows past the data.
An empty cell in a formatted column shows the column's format whether or not it has a record of its own. A record that names that same format adds bytes and nothing else.
What ShrinkExcel does
ShrinkExcel removes a cell record when it holds no value, no formula and no text, and names the format the cell would show without it. That is the row's format if the row has one, otherwise the column's, otherwise the workbook's default.
Where a row and a column both carry a format and the two differ, the record stays.
Some programs write placeholder cells marked as a text result with no value in them. Those count as empty. A cell that holds an empty string stays, because a formula such as ISBLANK tells an empty string from an empty cell.
A row goes once no cell is left in it and it sets nothing but its number. A row with its own height, format or outline level stays.
An empty cell whose format differs from its row's or column's keeps its record, since removing it would change what the sheet shows. Excess formatting deals with formatting beyond the data, and starts off.
What you will notice
Nothing on the sheet changes. Each removed record named the format its row or column already gives that cell, so the cell looks the same without it.
In a check in Excel for Mac on 2026-09-24, two workbooks shrunk this way held the same cells as their originals once Excel had opened and saved each copy.
It runs on every workbook you drop on the front page, unless you switch it off under Advanced settings.