Excel file extensions and their uses

  2. XLS vs XLSX
  3. XML and HTML
  4. XLTX and XLTM
  5. Excel for Mac
  6. Change file formats with Save As


A file extension is a group of letters that appear after the last dot in a file name. File extensions are 2 to 4 characters long and are linked to the file format Let’s take a look at the different types of file extensions Excel uses and see how you can change files from one format to another.

The information in this article applies to Excel 2019, Excel 2016, Excel 2013, Excel 2010, Excel 2007, Excel Online, and Excel for Mac.


The current default file extension for an Excel file is XLSX. Before Excel 2007, the default file extension was XLS. The main difference between the two is that XLSX is an XML-based open file format while XLS is Microsoft’s proprietary format. But newer versions of Excel save and open XLS files for compatibility with earlier versions of the program.

Determine if a file contains macros before opening it. Macros can contain malicious code that can damage files and compromise the security of your computer. Excel files with VBA and XLM macros use the XLSM extension.


XML stands for Extensible Markup Language. XML is associated with HTML (Hypertext Markup Language), an extension used for web pages. The advantages of this file format include:

  • Smaller file sizes for storage and transfer.

  • The best recovery of information from corrupted files.

  • Easier detection of files containing macros.


If the Excel file has an XLTX or XLTM extension, it will be saved as a template file. Template files are used as start files for new workbooks. The templates contain saved settings such as the default number of sheets for each workbook, formatting, formulas, images, and custom toolbars. The difference between these two extensions is that the XLTM format can store VBA and XML macros.

Excel for Mac

Macintosh computers do not rely on file extensions to determine which program to use when opening a file. However, for compatibility with the Windows version of the program Excel for Mac uses the XLSX file extension.

Excel files created on one operating system can be opened on another. The only exception is Excel 2008 for Mac, which does not support VBA macros. As a result, it cannot open XLMX or XMLT files created by Windows or later versions of Mac that support VBA macros.

Change file formats with Save As

Follow these steps to change the Excel file format (and its extension):

  1. Open the book you want to save in a different format.

  2. Select File

  3. Select Save as † Except for Excel 2019 where you choose Keep a copy

  4. In the dialog box, accept the suggested file name or enter a new name for the workbook.

  5. In the “Save as type” or “File format” list select the file format you want to use to save the file.

  6. Select Save to save the file in the new format and return to the current worksheet.

If the file is saved in a format that does not support all the features of the current format, such as formatting or formulas, a warning dialog box appears. You will be given the option to cancel and return to the Save As dialog box.

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