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How to Fix Excel for Mac Not Automatically Converting XLS Files to XLSX
Question details
Excel for Mac opens XLS files exported by third-party programs and continues saving them in the legacy XLS format instead of automatically converting them, despite Compatibility preferences being set to XLSX.
- Product
- Microsoft Excel
- Device & OS
- Mac
- Scenario
- A user is opening an older XLS file generated by an external application and trying to save it seamlessly in the modern XLSX format.
- Observed behavior
- Excel preserves the original legacy format of the opened workbook when saving, which can lead to data formatting errors, such as dates being treated as General format text.
Ensure your Excel for Mac is updated to the latest version, and verify that the file exported from your external program is truly an .xls file and not a CSV disguised with an .xls extension.
Manually Convert the XLS File Using 'Save As'
Because Excel's compatibility preferences only dictate the format for newly created blank files, you must manually use the 'Save As' function to convert an opened legacy file into an XLSX document.
By design, Excel always attempts to preserve the file format of an existing workbook when you hit 'Save'. This is to prevent unexpected compatibility issues for users who intentionally work with legacy files. To change the format, you must create a new copy using a different extension.
Launch Excel for Mac and open the exported XLS file.
Click on 'File' in the top Apple menu bar, then select 'Save As...' from the drop-down list.
In the Save dialog box, click on the 'File Format' dropdown menu and select 'Excel Workbook (.xlsx)'.
Click 'Save'. If Excel displays a compatibility warning about formatting or features, choose the option to continue and keep the new XLSX format.
Fix Broken Date Formatting with Text to Columns
If opening the older XLS file caused your dates to lose their formatting and display as General text or plain numbers, you can repair them using the Text to Columns tool.
Easily Manage and Convert Excel Files with WPS Office
WPS Spreadsheet provides a seamless and lightweight environment to open legacy XLS files, view them without formatting corruption, and save them easily to modern formats.
- 1. Open Your Legacy File: Launch WPS Spreadsheet and open the .xls file exported from your external program.
- 2. Open the Save As Menu: Click on the main 'Menu' button in the top left corner, then select 'Save As'.
- 3. Save as XLSX: In the file type dropdown menu, choose 'Microsoft Excel Workbook (*.xlsx)' and click save to safely convert the document.
Frequently Asked Questions
Why does Excel for Mac keep saving my files as XLS despite my preferences?
By default, Excel preserves the existing format of any opened workbook. The 'Compatibility' setting in Excel's preferences only configures the default format for newly created, blank spreadsheets, not for existing files.
Is there a way to force Excel to automatically convert all opened XLS files to XLSX?
No, Excel does not feature an automatic background conversion tool for opened files. You must manually initiate the format change using the 'File > Save As' command.
Can I just rename the file extension from .xls to .xlsx in Mac Finder?
No, manually changing the extension in Finder does not modify the internal structure of the file. Doing so will likely result in a corrupted file error when you attempt to open it in Excel.
Why do dates change to general numbers when opening an XLS file exported from another app?
This happens when the exporting program generates a raw data file (like a CSV or tab-delimited text) but mistakenly gives it an .xls extension, causing Excel to strip native date formatting upon import. Using the 'Text to Columns' tool can restore proper date formatting.
