You don't necessarily need Microsoft Excel to work with an .xlsx file Reviewed by Ryan Perian This article explains what XLSX files are, how to open them, and which programs are able to convert ...

Open the spreadsheet in Excel, click "File" and select "Save As." Choose the first "Excel Workbook" option to save the spreadsheet with an .xlsx extension.

If your Excel files are opening in Notepad on Windows PC, here's how you can reset the settings to make .xls, .xlsx, etc files open in Excel.

How to edit .xlsx files on Mac So, how do you edit an .xlsx file on a Mac? Due to the open file format used by Microsoft’s Excel software, it’s surprisingly easy to edit a .xlsx file on a Mac.

Also, if you're using multiple versions of Excel on the same computer, the default program for opening your files may be a different version of Excel than you'd prefer to use.