Excel: What Is the Native File Format for Excel? (original) (raw)
- Home
- Excel Tips Index
- Excel: What Is the Native File Format for Excel?
June 17, 2025
What’s up with XLS, XLSX, XLSB, XLSM? Which one should I use?
You should use XLSX.
XLS files were the only native file format up through Excel 2003. This file format cannot accommodate more than 65,536 rows. This format is known as a binary file format.
XLSB is the Excel 2007 equivalent of XLS. It is also a binary file format, but it can accommodate 1,048,576 rows.
XLSX is a new Excel 2007 file format where all of the data is saved in several XML files, then those files are zipped into a single XLSX file format. The result is smaller files. XLSX is a file format that does not allow macros. If you are reading this book, it is likely that you are not yet creating Excel macros in your workbook, so XLSX is fine.
XLSM is the same as XLSX, but macros are allowed. Since I routinely use macros, this is my favorite file type. But, there are downsides to this choice. For example, GMail refuses to offer a preview of XLSM files.
Excel also supports writing to two dozen other non-native file formats. Over the years, various competitors to Excel have pushed their own file formats. Excel still supports writing to mostly-defunct file types like SYLK, DIF. Microsoft is constantly adding to the list. Excel will now open and write files of the ODS file type. In the past, Excel would open files from Lotus 1-2-3 or Quattro Pro. If a company is seen as a credible alternative to Excel, Microsoft is likely to offer a way to open those files so people can come back to Excel.
There is one frustrating limitation to this policy. Excel for the Mac cannot open files created by Apple Numbers. The Excel for Mac team is separate from the Excel for Windows team. It seems that the Excel for Mac team is focused on adding features to Excel for Mac to keep it compatible with Excel for Windows. They don’t seem to have any interest in supporting the competitive files from Numbers. To get your data from Numbers to Excel, you will have to go back to Numbers and save in an Excel format.
FAQ – Choosing Between XLS, XLSX, XLSB, and XLSM in Excel
Which Excel file format should I use?
For most users, XLSX is the recommended format. It is modern, efficient, and supports all standard Excel features except macros.
What is the difference between XLS and XLSX?
XLS is the older binary format used before Excel 2007 and supports up to 65,536 rows. XLSX, introduced in Excel 2007, is XML-based, supports over 1 million rows, and produces smaller file sizes.
When should I use XLSM instead of XLSX?
Use XLSM if your workbook contains macros. Unlike XLSX, XLSM files can store VBA code. However, some email services like Gmail may not preview these files for security reasons.
What is the purpose of the XLSB format?
XLSB is a binary format like XLS but supports larger files and improved performance. It’s useful for very large spreadsheets, but less commonly used than XLSX or XLSM.
Can Excel open file formats from other spreadsheet software?
Yes. Excel supports opening and saving in many formats, including ODS (OpenDocument Spreadsheet), SYLK, and DIF. However, it cannot open files directly from Apple Numbers—you must export from Numbers to Excel format first.
This article is an excerpt from Don't Fear the Spreadsheet
Title photo by Rubaitul Azad on Unsplash