Excel File Formats: A Complete and Practical Guide to Extensions

Working with Excel often involves dealing with a wide variety of file formats, which can raise questions or even compatibility issues if you're not familiar with them. Correctly managing file extensions and formats in Excel is essential to getting the most out of the program and avoiding problems, data loss, or unnecessary incompatibilities. Whether you're working with different versions, need to exchange data with other programs, or simply want to optimize the performance of your spreadsheets, knowing what each extension means and when to use it can save you a lot of time and headaches.

In this article we are going to make a A comprehensive and practical review of all the formats supported by Excel and what role each one plays: from the classic .xlsx and .xls to lesser-known ones like .xltm, .xlsb, .ods, and .mhtml. You'll also understand their purposes, their advantages, limitations, and the cases in which choosing one over the other is more convenient. Get ready to resolve any doubts and become a true Excel file expert.

Why are there so many file formats in Excel?

The diversity of file formats in Excel is not a coincidence, but the result of years of program evolution and the adoption of different user needs. Since its first versions, Excel has been adding new extensions depending on the technical capabilities of each era and the demand for interoperability with other systems and applications. Thus, today we find a true constellation of formats that range from classic spreadsheet work to the advanced automation with macros, integration with databases, web publishing and sharing information in portable format.

Another key factor is backward compatibility, as many companies and users retain documents from decades ago. Excel still supports older formats such as .xls or .xlt, but since 2007 it has also incorporated XML-based formats (Open XML), such as .xlsx or .xlsm, which offer greater security, better compression and greater versatility for external integrations.

Main Excel file formats

These are the most commonly used formats in the daily work of any Excel user. They all have their own characteristics and limitations that are worth knowing.

• .xlsx (Excel Workbook): This is the default format from Excel 2007 onwards. Based on the Open XML standard, improves security and performance compared to .xls. It doesn't allow storing macros or VBA code. It's ideal for conventional spreadsheets without automation.
• .xlsm (Macro-enabled workbook): Practically the same as the previous one, but adds the possibility of saving macros and VBA code to automate tasks. If your file has macros, you should save it with this extension.
• .xls (Excel 97-2003 Workbook): It is the classic (binary) format prior to the XML era. It is used for compatibility with older versions, although it lacks many of Excel's modern features. It's still useful if you need to share files with users who haven't updated their Office suite.
• .xlsb (Excel Binary Workbook): Here Excel saves the file in a binary format instead of XML. It is much faster to open and save very large files and also supports macros. Perfect for spreadsheets with large amounts of data or for those seeking maximum performance.
• .xltx (Excel Template): Allows you to create reusable templates without macros. Whenever you want to create new workbooks based on a common template, use this format.
• .xltm (Macro-enabled template): Same as above, but with macro support. If your template includes automations, this is the appropriate format.
• .xlt (Classic Excel 97-2003 Template): Legacy binary format, for templates in older versions. Use only if you need full backwards compatibility.

Text formats: data exchange and universal compatibility

Excel also allows you to save and open files in universal text formats. These formats are essential for import or export data to other programs, databases and systems.

• .csv (Comma-Separated Values): The text file with comma-separated values ​​is the star format for importing and exporting data. Allows you to easily move data between Excel and any other software (databases, web applications, management systems, etc.). There are variations depending on the operating system (Windows, Macintosh, MS-DOS), but they all share the simplicity and portability of the format.
• .txt (Tab-delimited text): Similar to CSV, but fields are separated by tabs instead of commas. Indicated when the data contains commas and the aim is to avoid confusion.There are versions for Windows, Macintosh, and MS-DOS, plus the option to save as Unicode text to support special characters from any language.
• .prn (Space-delimited formatted text): Inherited from older Lotus programs, this format organizes data using blank spaces as separators. Very useful in certain older environments.
• .dif (Data Interchange Format): Old and still supported, it allows data exchange with some specialized systems and programs.
• .slk (SYLK: Symbolic Link Format): Another classic format for exchanging with legacy systems and non-Microsoft spreadsheets.

Formats for interoperability and data openness

• .xml (Extensible Markup Language): Excel allows you to work with XML files for both data (information structure) and complete spreadsheets (XML Spreadsheet 2003). This article on compression formats may be interesting to understand how to optimize the size of your XML files in Excel when compatibility and fast opening are a priority.
• .ods (Opendocument Spreadsheet): This is the open standard format used by suites such as LibreOffice or OpenOffice. For several versions, Excel has supported opening and saving .ods files., thus facilitating collaboration in mixed environments.

Export and web publishing formats

• .htm and .html (Web page)When you save an Excel file as a web page, you get a folder containing supporting files for the spreadsheet's multimedia elements and scripts. This is very useful for publishing tables and data directly to the web, although somewhat obsolete compared to other modern solutions.
• .mht and .mhtml (Single File Web Page): A more advanced variant of simple HTML, as it stores all the necessary resources in a single file. Here you can learn how to convert tables from Excel to Word and make publishing them easier. on websites or presentations.

Formats for compatibility with databases and specialized programs

• .dbf (dBase III/IV)Excel allows you to open files in this veteran database format, although it no longer allows you to save them directly to .dbf. This is useful for importing data from older systems.

Read-only formats and formatting preservation for printing and archiving

• .pdf (Portable Document Format): Essential for sharing reports, budgets, or any Excel document that needs to retain its exact format, both on screen and in print. PDF files They cannot be easily edited, which helps ensure the integrity of the information.
• .xps (XML Paper Specification): Less known than the PDFXPS is Microsoft's alternative for preserving document formatting. Its use is similar, although less widespread outside the Windows ecosystem.

Plugin Formats and Advanced Automation

• .xlam (Excel Add-ins): This format is used for VBA-programmed add-ins and custom functions that are automatically loaded into Excel to extend its capabilities. They allow you to run code and add new functions to every file you open.
• .xla (Excel 97-2003 Classic Add-in): Older version of the plugins, aimed at compatibility with older version environments.

Additional formats supported by Excel

• .xlw (Excel 4.0 Workbook)Although it's almost a relic, Excel 4.0 allows you to save and open this format, which only supports spreadsheets, charts, and macros. Today, it can only be opened, not saved.
• .xlr (Works Spreadsheet 6.0-9.0): Supported for opening legacy Microsoft Works files.

Formats used by the Office clipboard

El clipboard de Microsoft Office can handle a variety of formats when copying and pasting from Excel. In addition to image formats (.wmf, .emf, .bmp), it also supports native Excel formats, text, CSV, SYLK, DIF and RTFThis is essential when sharing data between applications, allowing information to travel in its format or automatically adapt to its destination.

Unsupported and discontinued formats

Over time, Excel has discontinued support for certain legacy formats that no longer meet current needs or technological standards. Some examples of unsupported formats (which cannot be opened or saved) include:

• .xlc (Excel 2.0/3.0 Charts)
• Lotus 1-2-3 formats (.wk1, .wk2, .wk3, .wk4, .wks)
• DBF2 (dBase II)
• .wb1, .wb3, .wq1 (Quattro Pro)

In case you need to work with any of them, It is possible to use third-party programs specialized in format conversion or first transform the file into an intermediate compatible format.

Tips for choosing the right format in Excel

• To work with the most modern and secure version, use .xlsx whenever possible. if you don't need macros, or .xlsm if you do use them.
• If you handle large volumes of data and are looking for more speed, give .xlsb, the binary format, a try.
• For shared templates without macros, .xltx is ideal; with macros, choose .xltm.
• To share data with other systems or import/export, .csv and .txt are irreplaceable.
• Do you need full portability and edit lock? Save your report as a PDF or XPS.
• If the recipient uses LibreOffice/OpenOffice, choose .ods.

Frequently Asked Questions About Excel Formats

• Can I open older .xls files in modern Excel? Yes, they will open in compatibility mode. It's recommended to convert them to .xlsx to take advantage of the latest features.
• Can I save .xlsx files as .pdf? Yes, Excel allows you to export directly to PDF while preserving both the layout and visual formatting.
• What happens if I save a sheet with macros in .xlsx? You'll lose your macros. To preserve them, you must use .xlsm.
• What is the difference between .xlsb and .xlsx? The first is a binary format and is usually faster with large amounts of data or complex files. The second is more standard and has been the default since 2007.
• Are there security risks when using macros? Yes. That's why Excel distinguishes between macro-enabled and non-macro-enabled formats. Don't open files with macros from unknown sources.

The hidden structure of Excel extensions: how to interpret them

Since the arrival of Open XML formats, Excel extensions have followed a clear logic:

• The first two letters (xl) indicate Excel.
• The third letter indicates the type: s (spreadsheet), t (template), a (add-in).
• The last letter reveals the technology: x (XML), m (macro-enabled), b (binary).

For instance, .xlsb It is a binary book, .xltx It is a macro-free XML template, .xlsm It is an XML book with macros. This article explains how to fix file extension and format incompatibilities..

Limitations when saving in other formats

Some formats do not support all Excel features:

• Saving as .csv or .txt means losing formatting, formulas, charts, multiple sheets, and macros..
• The .ods format may cause minor loss of formatting or advanced functionality when opened in Excel.
• When exporting to .pdf or .xps, everything is visual only: there will be no editable data in Excel.

Practical tips to avoid problems

• Before saving to a different format, back up the original file.
• If you share files with other people, ask which version and program they will be working with to choose the most appropriate format.
• Use descriptive names to determine if the file contains macros or is just a template.
• Make sure you don't lose important data when moving from Excel to a plain text file.

Related article:

Compression Format Comparison: Which One Offers the Highest Capacity?

Mastering the different Excel file formats will allow you to Optimize your workflow, prevent compatibility issues, and get the most out of your spreadsheets.Knowing when to choose each format is like having the keys to every door in the program: from macro automation, databases, web integrations, or simple imports and exports, each extension has its purpose. Next time you hit "Save As..." do it with confidence and choose the format you really need.

Isaac

Passionate writer about the world of bytes and technology in general. I love sharing my knowledge through writing, and that's what I'll do on this blog, show you all the most interesting things about gadgets, software, hardware, tech trends, and more. My goal is to help you navigate the digital world in a simple and entertaining way.