What Is an XLSX File?

This article explains what XLSX files are, how to open them, and which programs are able to convert them to other spreadsheet formats like CSV or ODS.

What Is an XLSX File?

A file with the XLSX file extension is a Microsoft Excel Open XML Format Spreadsheet file. It's a ZIP-compressed, XML-based spreadsheet file created by Microsoft Excel version 2007 and later.

XLSX files organize data in cells that are stored in worksheets, which are in turn stored in workbooks (files that contain multiple worksheets). The cells of a spreadsheet are positioned by rows and columns and can contain styles, formatting, math functions, and more.

Spreadsheet files made in earlier versions of Excel are saved in the XLS format. Excel files that support macros are XLSM files.

How to Open an XLSX File

Unless you've purposely installed a program to your computer that can open XLSX files, then double-clicking on one won't do anything useful. Instead, you need to have a specific program on your computer that can recognize the XLSX file.

Although Microsoft Excel (version 2007 and newer) is the primary software program used to both open XLSX files and edit XLSX files, you can install the Microsoft Office Compatibility Pack to open, edit, and save XLSX files using an older version of Excel.

If you have no intention to edit the XLSX file, and you just want to view it, you can install the free Microsoft Excel Viewer. It supports printing and copying data out of the XLSX file, too, which might be all you need to do.

You can also open and edit XLSX files without Excel, completely free, using WPS Office Spreadsheets, OpenOffice Calc, or LibreOffice Calc. If you're on a Mac, Apple Numbers supports XLSX files, too (but not all features will work).

Google Sheets, Microsoft Excel Online, and Zoho Docs are a few other ways you can open and edit XLSX files for free. Going this route requires you to upload the XLSX file to the website before you can make any changes.

If you use the Chrome web browser, you can install Office Editing for Docs, Sheets & Slides as an extension, which lets you open and edit XLSX files directly in the browser, either by dragging a local XLSX file into Chrome or opening one from the internet without having to download it first.

How to Convert an XLSX File

If you have one of the applications we've already mentioned installed on your computer, it's recommended to use that same program to save whatever XLSX you're working with to the specific format you're interested in. This is normally done through the File > Save as menu option.

For example, if you're using Excel, go through its FILE > Save As > Browse menu and choose CSV, XLS, TXT, XML, etc. The F12 key should also work to get to the Save As window.

Sometimes the quickest solution to convert an XLSX file isn't with a tool you have installed, but instead via a free file conversion software program or online service like Zamzar.

Just looking at the capabilities of those two services, you can convert whatever Excel file you have to many different file types, like XLSX to CSV, XML, DOC, PDF, ODS, RTF, XLS, MDB, and even image and web file formats like JPG, PNG, and HTML.

TinyWow can split an Excel file if you want the XLSX file to end up as multiple files. That same site has an Excel to XML converter, and others that can save the file to PDF or CSV.

Still Can't Open the File?

The most likely reason for why the file won't open at this point, if you've tried all the suggestions above, is that you're not really dealing with an XLSX file. This might happen if you've only briefly looked at the file extension and are confusing it for an Excel file.

For example, maybe your file really ends in .LSX, in which case it's a Streaming Media Shortcut file and has nothing to do with Excel. Windows Media Player opens LSX files.

Similarly, it'd be easy to confuse an SLX file for one that has the Excel XLSX suffix, but SLX files are also unrelated to Excel and are instead used by programs like Simulink and SpectraLayers.

XLR is another one that's easy to mix up for an Excel file.

If you can't open the file, re-read the extension and research it online. It should be fairly easy to find more information about the format and learn which programs are able to open and convert it. We may even have a description of it here on Lifewire—use the search box at the top of this page to check.