XLS to XLSX Converter
Upgrade your spreadsheets. Convert old .xls files to the modern .xlsx format for full compatibility with newer Excel versions.
Why Convert XLS to XLSX?
The .xls format, used until Excel 2003, is outdated and has limitations on rows and columns. Converting to .xlsx uses the modern XML-based format, which results in smaller file sizes, better data recovery, and support for over a million rows.
Upgrading to the XLSX format ensures your spreadsheet files remain fully compatible with Microsoft 365, Office 365, Google Sheets, and other modern data analysis tools and spreadsheet applications, while also benefiting from improved security features and significantly better data recovery capabilities.
How to Convert XLS to XLSX
- Upload your legacy .xls workbook.
- The tool converts the structure to modern XML .xlsx.
- Click 'Convert' to finish.
- Download your upgraded Excel file.
Key Features of MiConvert XLS to XLSX
- Upgrade legacy Excel files
- Reduced file size
- Preserves data and formatting
- Supports multi-sheet workbooks
- Secure conversion
- Free to use
Video Tutorial
Watch this step-by-step tutorial to learn how to convert XLS files to XLSX format online for free using MiConvert.com. No software installation required.
Frequently Asked Questions
Will I lose my formulas?
Most standard Excel formulas and functions are preserved and transferred to the new XLSX format seamlessly without any manual adjustments needed.
Are macros kept?
No, this conversion produces a standard .xlsx file which does not support macros. If you need macros, you would typically convert to .xlsm, which this specific tool does not output.
Is the new file smaller?
Yes, XLSX is a compressed XML-based format, so your spreadsheets will typically take up significantly less storage space compared to the older XLS format.
Can I open it in old Excel?
Excel 2007 and all newer versions open XLSX files natively. Older versions such as Excel 2003 may need a free compatibility pack from Microsoft.