XLS or XLSX file ?

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Since Excel 2007, you can save your Excel file with the extension xlsX. What the last X means ?

XLSX, What means the last X?

XML is a computer language. It means eXtensible Markup Language.

In fact it's a language where all the data are ordered. No easy to understand for human but for a computer, when data are ordered it's easier to store and to read.

Reduce the size of your Excel files

XML is a language that compress automatically the data. So when you save your XLS file to XLSX, the size of your document will be reduce.

File size xls vs xlsx

Extension of the working area.

In a Xls workbook, the row limit is 65,536 (216) and 256 columns (28) which corresponds to the column IV.

Now with xlsx workbooks (and xlsm), limits are 1,048,576 rows (220) and 16,384 columns (214) or the column XFD.

With a xlsx file, you have more than one million rows

Protection against macros

  • .xlsX workbooks have no macro
  • .xlsM,  workbooks have macros

We have seen that the last x of a xlsx file indicates that the file is compressed and respects the XML standard. The M, of a xlsm file, indicates that the file contains macros.

A macro is a program written by an end-user to provide an automation (opening files, data comparison, data aggregation across multiple sheets, ...) but also a program may cause malfunctions. In addition, a macro can run directly when you open an Excel file, without prompting the user.

With an xls file, you don't know whether your workbook contains macros or not. When you receive a xlsx file, you are sure that non-expected codes are in your file.

Work with Tables

Menu Table

Tables are very useful to create dynamic functions, change the design quickly or select easily rows or columns.

But Tables are only available with xlsx files. If you save your work to xls, your Tables will be destroyed and un-usable.

Embed file in a website

The following element is not an image but a worksheet. You can edit cells or create formulas 😮😮😮

XML documents can be embed in a website so only Excel file with the extension xlsx can be integrated in a website

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1 comment

Dick 23/02/2018 at 17:55

The draw back to .xlsx & .xlsm is that they (xlsx & xlsm) take as much as 3 times longer (in time) to open.
I made a file and saved it down as .xlsx. Then I saved down the same file as .xls. Agreed, the .xls file shows that it's much larger, but it only took 4 seconds to open as to where the .xlsx file took about 18 seconds to open. I'm not ready to get rid of my .xls files because of this.


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