New Office File Formats

With the release of Office 2007, Microsoft have taken the opportunity to overhaul the Office file formats for Word, Excel, and PowerPoint.

The new Office file formats are known as the Microsoft Office Open XML file formats, and are themselves derivatives of the XML (Extensible Markup Language) file formats commonly used in Web applications.

The .doc, .xls and .ppt file extensions are now .docx, .xlsx and .pptx, and also have a slightly different extension again if the file contains macros.

The move to the new format has two distinct advantages for the average user.

  1. File sizes are half that of their previous versions.
  2. The new format is actually a ‘container’ for their many different elements that make up your document, such a pictures or styles (in a PowerPoint file each slide is actually stored separately). This makes it much easier to retrieve data if corruption occurs as you are likely to only lose the corrupted file, not the whole ‘container’.


.docx – Word document.
.docm – Word document with macros.
.dotx – Word template.
.dotm – Word template with macros.



.xlsx – Excel document.
.xlsm – Excel document with macros.
.xltx – Excel template.
xltm – Excel template with macros.
.xlsb – Non XML binary workbook.
.xlam – Excel add-in with macros.



.pptx – PowerPoint presentation.
.pptm – PowerPoint presentation with macros.
.potx – PowerPoint template.
.potm – PowerPoint template with macros.
.ppam – PowerPoint add-in with macros.
.ppsx – Auto running PowerPoint slideshow.
.ppsm – Auto running PowerPoint slideshow with macros.
.sldx – PowerPoint slide.
.sldm – PowerPoint slide with macros.

Ostensibly, files created by Microsoft Access remain unchanged from previous versions of Office

These are the standard Office 2007 file formats, by using the ‘Save As’ command it is possible to save your work in a variety of other formats including .pdf. (You will need to download the free plug-in from Microsoft for this)

It is possible in most of the programs to open files created in older versions of Office, and in a new departure Microsoft have made it easy to open documents created with Office 2007 in previous versions, although you need to download the Microsoft Office Compatibility pack from their website to do so.