What are the new document formats used in Microsoft Office 2007?

With the introduction of Microsoft Office 2007, Microsoft included new formats for three of the primary Office programs:

  1. Microsoft Word - A word processing program used for typing documents and letters.
  2. Microsoft Excel - A spreadsheet program used for storing data in rows and colums and performing calculations on the data.
  3. Microsoft PowerPoint - A presentation program used for creating professional presentations and slide shows.

New File Format

In Office 2007 (also known as Office 12), these three programs will use a new file format based on Open XML. Word, Excel, and PowerPoint documents will be saved in an XML format rather than binary. This will make it possible for damaged files to be recovered, since the way XML stores data allows the file to be viewed even if part of the document is corrupted. For example, if an Open XML Word Document contains a damaged chart, the chart may not show up correctly, but the rest of the file should look fine. If the file was saved as a binary document, it may not even open.

Smaller File Size

Besides incorporating a new, more compatible format, the new Office documents take up less space than previous formats. This is because the new format incorporates ZIP compression, which can reduce file size up to 75%. This saves hard drive space, and is beneficial when sending documents over the Internet, via e-mail or other data transfer methods.


Since XML is a standardized format, Open XML documents are recognized by any software that supports the Open XML format. While previous versions of Office programs do not natively support documents saved in the new format, Microsoft has released updates for Office 2000, XP, and 2003, that allow users to open, edit, and save documents in the Open XML format.

File Extensions

The new Open XML Office formats will include new file extensions to distinguish them from the previous file types. The extensions of the new and old file types are listed below:

New Extension Old Extension File Type
Microsoft Word
.DOCX .DOC Word Document
.DOCM n/a Macro-enabled Word Document
.DOTX .DOT Word Document Template
.DOTM n/a Macro-enabled Word Document Template
Microsoft Excel
.XLSX .XLS Excel Spreadsheet
.XLSM n/a Macro-enabled Excel Spreadsheet
.XLTX .XLT Excel Spreadsheet Template
.XLTM n/a Macro-enabled Excel Spreadsheet Template
.XLSB n/a Excel Binary Workbook
.XLAM .XLA Excel Add-in
Microsoft PowerPoint
.PPTX .PPT PowerPoint Presentation
.PPTM n/a Macro-enabled PowerPoint Presentation
.PPSX .PPS PowerPoint Slide Show
.PPSM n/a Macro-enabled PowerPoint Slide Show
.POTX .POT PowerPoint Presentation Template
.POTM n/a Macro-enabled PowerPoint Presentation Template
.PPAM .PPA PowerPoint Add-in

Microsoft Access

Microsoft Access 2007 also uses a new database format with an .ACCDB file extension. (Previous versions of Access saved databases as .MDB files.) The new format supports multi-valued fields, binary objects, database encryption, and other new features.

The other Office formats, such as Visio and Entourage (Mac) files, remain the same.