Open XML Formats and file name extensions

How do I convert my file from the old binary format to the modern Open XML format?

With the file open in your Office app, click File > Save as (or Save a copy, if the file is stored on OneDrive or SharePoint) and make sure the Save as type is set to the modern format.

This will create a new copy of your file, in the Open XML format.

What are the XML file name extensions?

By default, documents, worksheets, and presentations that you create in Office are saved in XML format with file name extensions that add an "x" or an "m" to the file name extensions that you are already familiar with. The "x" signifies an XML file that has no macros, and the "m" signifies an XML file that does contain macros. For example, when you save a document in Word, the file now uses the .docx file name extension by default, instead of the .doc file name extension.

When you save a file as a template, you see the same kind of change. The template extension used in earlier versions is there, but it now has an "x" or an "m" on the end. If the file contains code or macros, you must save it by using the new macro-enabled XML file format, which adds an "m" for macro to the file extension.

The following tables list all the default file name extensions in Word, Excel, and PowerPoint.