File Formats and Extensions

Excel files can have different extensions depending on the type and format of the data they contain. The most common extension is .xlsx, which is the default XML-based file format for latest versions.

Since the release of Office 2007, all workbook files are saved in an “Open XML” file format by default (a compressed zip file). This file format uses four-letter file extensions (.xlsx, .xlsm, .xlsb, .xltx, .xltm, and .xlam).

Using the XML file format, a developer or a third-party application can easily edit the workbook without having the Office application installed on their computer. In this tutorial, you’ll see what a file extension tells you about itself.

We can break the latest Excel file extensions types into three parts:

  1. The first and second letters of the file extension refer to the application:
    • xl = Excel
  2. The third letter refers to the specific file type:
    • s = Spreadsheet
    • t = Template
    • a = Add-in
  3. The last letter specifies whether the file format is XML based or it supports macros:
    • x = XML-based file format, can’t store VBA macro code
    • m = Macro-enabled and XML-based file format
    • b = Binary file format (support faster loading and saving). This non-XML-based file format can store VBA macro code.

File Extensions Since Excel 2007

.xlsx = Excel Workbook
It is the default Excel file format (does not support VBA/Macros).

.xlsm = Excel Macro-Enabled Workbook
If your workbook contains VBA code or macros use this file format.

.xlsb = Excel Binary Workbook
The binary file format, this format is optimized for the faster loading of really large workbooks with tons of data.

.xltx = Excel Template
An Excel template file can use to generate new workbooks containing the same layout and content as the template.

.xltm = Excel Macro-Enabled Template
An Excel template file format with all the macros it contains enabled.

.xlam = Excel Add-in
An Excel add-in is a workbook that gives additional functionality to any workbook. It can be opened by default when Excel starts up or loads.

Excel 97-2003 file extensions

.xls = Excel Workbook
This binary file format is used by earlier versions of Excel 97 through Excel 2003.

.xlt = Excel Template
Binary files for an Excel template.

.xla = Excel Add-in
Binary files for an Excel add-in.

Open source spreadsheet programs file extension

.ods = OpenDocument Spreadsheet
You can save (or open) a workbook in ODF format with an .ods filename extension that’s used by other Office suites of programs, such as StarOffice OpenOffice.

Other file formats supported in Excel

  • .csv = Comma delimited text file
  • .dbf = dBase file format
  • .dif = Data Interchange Format
  • .htm, .html = Web-Page, saved in a folder, all supporting files saved in that folder.
  • .mht, .mhtml = Single File Web Page, includes all supporting files, such as images
  • .pdf = Portable Document Format, this format preserves file formatting when sharing with others.
  • .prn = Lotus space-delimited format.
  • .slk = Symbolic Link Format
  • .txt = Plain text file
  • .xml = XML file format
  • .xps = XPS Document

Understanding Workbooks and Worksheets: