Convert legacy XLS files to modern XLSX format instantly. Upgrade Excel 97-2003 spreadsheets to the Open XML format with better performance, security, and compatibility. Batch process multiple files. No signup, secure, and free.
Follow these easy steps to upgrade your legacy Excel files to the modern XLSX format:
Click the upload area or drag and drop your legacy .xls files. Selected files appear in the order they'll be converted.
Drag and drop files in the list to rearrange them. The order determines the sequence of converted XLSX files.
Once files are arranged, click the Convert to XLSX button to start upgrading your Excel files.
Download your converted modern XLSX files. All original XLS files are automatically deleted from our servers for your privacy.
Pro Tip: XLSX files offer up to 1 million rows (vs 65,536 in XLS), better compression (smaller file size), improved security, and full compatibility with modern spreadsheet applications including Microsoft Excel, Google Sheets, and LibreOffice.
Our XLS to XLSX converter helps you upgrade legacy Excel 97-2003 spreadsheets to the modern Open XML format. XLSX files offer superior performance, smaller file sizes, enhanced security, and support for advanced features like more rows, columns, and better data visualization. No installation, no signup, just fast and secure conversion.
We ensure seamless upgrade from legacy to modern Excel format:
| Formula preservation: All formulas remain functional | Formatting retained: Cell styles, colors, borders preserved |
| Chart & image support: Visual elements converted intact | Batch efficiency: Process multiple files simultaneously |
| Secure transfer: HTTPS encryption throughout | Auto-delete: Files removed after 1 hour |
Upgrade legacy business spreadsheets for modern data analysis tools.
Enable larger datasets with XLSX's 1 million row capacity.
Take advantage of XLSX's improved security features.
Reduce storage space with XLSX's superior compression.
Ensure files work with modern Excel and Google Sheets.
Access newer Excel features like slicers and timelines.
| Feature | XLS (Legacy) | XLSX (Modern) |
|---|---|---|
| Maximum Rows | 65,536 | 1,048,576 |
| Maximum Columns | 256 | 16,384 |
| File Format | Binary (BIFF) | Open XML (ZIP-based) |
| File Size | Larger | Compressed, smaller |
| Security Features | Limited | Advanced encryption |
| Compatibility | Legacy applications | All modern spreadsheet tools |
Upgrade your legacy Excel files to the modern XLSX format. Perfect for businesses, data analysts, and anyone who needs to work with modern spreadsheet applications.