Since the release of Microsoft Office 2007, Excel has used the .xlsx format as its default file extension. This modern, XML-based format offers significant advantages, including smaller file sizes, better data recovery, and support for massive spreadsheets with millions of rows. However, if your workplace relies on bespoke, legacy database software (such as older ERP systems or custom accounting portals), you may find that these systems physically cannot import .xlsx files and explicitly demand the older 1997-2003 .xls format. Rather than manually selecting “Save As” and hunting through the dropdown menu every single time you finish a report, you can force Excel to save as .xls by default.
How to Change the Default Save Format
You can adjust this behaviour deep within Excel’s global Options menu. The change will apply to all future blank workbooks you create on this specific computer.
- Open Microsoft Excel.
- Click on the File tab located in the top-left corner of the window.
- Look at the bottom of the left-hand blue sidebar and click on Options. (If your window is small, you may need to click ‘More…’ first to reveal Options).
- The “Excel Options” dialogue box will appear. In the left-hand menu pane, click on Save.
- Look at the very top section on the right, titled “Save workbooks”.
- Locate the drop-down menu labelled Save files in this format:.
- Click the drop-down menu, scroll through the list, and select Excel 97-2003 Workbook (*.xls).
- Click the OK button at the bottom right of the window.
A Warning Regarding Features and Size
Once applied, whenever you press Ctrl+S to save a new file, Excel will automatically choose the .xls format.
Be aware that the legacy .xls format has strict physical limitations. An .xls file can only hold a maximum of 65,536 rows (compared to the 1,048,576 rows supported by .xlsx). Furthermore, modern features like Sparklines, advanced conditional formatting rules, and newer array formulas are not supported in the old format. If you use these features and then attempt to save, Excel will present a “Compatibility Checker” warning, alerting you that the data will be flattened or lost in the conversion.