The Microsoft Excel .XLSX File Extension

Microsoft Office 2007’s File Extensions

Though it’s been several years since Microsoft Office 2007 debuted, the file extensions associated with its programs continue to baffle computer users. For example, if you’ve ever used Microsoft Excel, you likely recognize the .xls file extension as representing an Excel file. If you have Excel 2003 or a compatible spreadsheet program on your computer, you can easily handle .xls files. But what about .xlsx files? Microsoft Excel 2007 doesn’t save spreadsheets as .xls files, it saves them with the new .xlsx file extension.

Problems with New File Extensions

When new file extensions are introduced, such as when Microsoft introduced the .xlsx file extension, it’s not unusual for users to have difficulty opening them. After all, if you’re using an older program to open a file extension that was since developed, incompatibility issues are bound to arise.

In addition to the incompatibility issue, it’s not easy to figure out what an unfamiliar file actually is. Searching an Internet file extension library is a good way to learn about new file extensions as is using a product such as FileCure which features a huge, frequently updated database of file extensions. Armed with information, you will be better prepared to deal with a previously unknown file extension.

Opening the File Extension XLSX

So, what should you do if you receive an .xlsx file from a friend or colleague? If you have Excel 2007, you won’t have a problem opening it because you have the correct application for the job. However, if you do not have Excel 2007, it’s doubtful that you’ll be interested in investing in the program simply to view a single .xlsx file. Fortunately, Microsoft understands this dilemma and offers a free Excel 2007 viewer program specifically for viewing files created by Excel 2007. The XLSX viewer program has its limits; it’s for viewing and printing only. Don’t expect to be able to edit the .xlsx file or create new spreadsheets with this program. You can download the Excel 2007 from

If you have an older version of Excel installed on your computer, head over to and download its Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007. Once your existing version of Office is updated, you will be able to work with .xlsx files. Another option is to download the free suite and use its Calc program to open the .xlsx file.  

The .xlsx file extension, and any unfamiliar file extension for that matter, may be tricky to deal with at first, but once you’ve found the right information, such as searching through a file extension library, and found the right program for opening it, you’ll be on your way to accessing the data held within.  

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