Upgrade legacy Excel .xls files to the modern .xlsx format. All sheets and data preserved. Runs entirely in your browser.
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Drop an .xls file or browse
Legacy Excel 97–2003 format
XLS to XLSX upgrades legacy Microsoft Excel .xls files (Excel 97–2003 binary format) to the modern .xlsx format (Office Open XML). XLSX files are smaller, more compatible, and supported by all modern apps.
Drop your .xls file. SheetJS reads the legacy binary format, preserving all sheets, cell data, formulas, and basic formatting. It then writes the data as a modern .xlsx file — entirely in your browser. Nothing is uploaded.
Upload your XLS file
Drop an older .xls Excel 97-2003 file onto the upload zone.
Convert
Click "Convert to XLSX". The file is converted to the modern Open XML Excel format.
Download
Save the .xlsx file and open it in Microsoft Excel 2007+, Google Sheets, or LibreOffice Calc.
Edit freely
XLSX supports all modern Excel features including larger datasets and advanced formulas.
Legacy Data Archives
Upgrade XLS spreadsheets created in the late 1990s or early 2000s to XLSX so they open cleanly in modern Excel versions.
Business Reporting
Convert old .xls financial or inventory reports to XLSX before importing them into modern BI tools or databases.
Large Datasets
XLS is limited to 65,536 rows — converting to XLSX removes that restriction and supports over a million rows.
Cloud Collaboration
Upload spreadsheets to Google Sheets or Microsoft 365 online, which require XLSX for full editing functionality.
Formula Modernization
Convert legacy XLS files to XLSX to gain access to modern Excel functions and array formulas not available in the old format.
Cross-App Sharing
Share spreadsheets with LibreOffice or Google Sheets users who handle XLSX more reliably than the binary XLS format.
Browser-Only Processing
SheetJS processes your XLS file entirely in the browser — no file is uploaded to any server.
All Data Preserved
Every sheet, cell value, formula, and basic structure is faithfully transferred to the output XLSX file.
Row Limit Removed
XLSX supports 1,048,576 rows versus the old 65,536-row XLS limit, future-proofing your spreadsheet.
Smaller File Size
XLSX uses ZIP-based compression so the output file is typically smaller than the equivalent XLS binary.
Password Protection Transparency
The tool clearly informs users that password-protected files must be unlocked first, avoiding silent failures.
Free to Start — Sign Up for More
Use free with no account for files up to 40 MB. Sign up free to raise your limit to 80 MB, or upgrade to Pro for 250 MB per file.
Also Known As
Excel to PDF
Convert XLS and XLSX spreadsheets to PDF, keeping all rows and columns.
PDF to Excel
Extract tables from PDFs and convert them to editable Excel spreadsheets.
Excel to CSV
Export an Excel spreadsheet to CSV for use in any data application.
CSV to Excel
Import a CSV file into a structured Excel XLSX spreadsheet.
Excel to JPG
Capture each sheet of an Excel file as a JPG image.
ODS to Excel
Convert LibreOffice Calc ODS files to Excel XLSX format.
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