Convert XLS to XLSX Online
XLS is the old binary Excel format from the 1990s. Converting to XLSX gives you the modern open XML format that works with Excel 365, Google Sheets, and LibreOffice Calc.
Our converter handles all XLS files from Excel 97/2000/2003 and produces fully compatible XLSX output.
What is XLS?
XLS is Microsoft Excel's older binary spreadsheet format used in Excel versions before 2007. It has a 65,536 row limit and uses an older binary encoding.
XLS files have an outdated row limit, less compatibility with modern applications, and binary encoding that can cause issues with non-Microsoft software.
What is XLSX?
XLSX uses the Office Open XML standard, stores data as XML in a ZIP archive, supports over 1 million rows, and is fully compatible with all modern spreadsheet applications.
Converting XLS to XLSX removes the old row limit, improves compatibility, and makes your spreadsheets ready for modern collaborative workflows.
Why Convert XLS to XLSX?
Modern Compatibility
XLSX works perfectly with Excel 365, Google Sheets, LibreOffice Calc, and Numbers.
More Rows
XLSX is the standard format for sharing spreadsheets with colleagues on any platform.
Better Collaboration
XLSX is the standard format for sharing spreadsheets with colleagues on any platform.
Open Standard
XLSX is an ISO standard format with long-term support guaranteed.
How to Convert XLS to XLSX
Upload XLS
Select your old XLS file.
Choose XLSX output
Select XLSX as your output format.
Convert
Click convert to modernize your spreadsheet.
Download XLSX
Save your modern XLSX file.
Ready to Convert XLS to XLSX?
Use our free online converter. No signup, no watermarks, no limits.
Convert XLS to XLSX NowPro Tips
Check formulas after conversion
Verify that all formulas work correctly after conversion, especially complex ones.
Check charts and formatting
Review charts and conditional formatting to ensure they converted accurately.
Update your default format
Set Excel to save as XLSX by default in Excel Options.
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Our converter handles all XLS files automatically with no quality loss.
Files are processed securely and deleted after 1 hour for your privacy.
Convert XLS to XLSX Now