Free Online XLS Converter
The legacy Excel workbook, from before XLSX replaced it.
Up to 50 MB per file. Sign up free to convert files up to 100 MB.
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Checking files and selected output formats.
How to convert XLS files online
Convert legacy Excel 97-2003 XLS spreadsheets to modern formats without needing older versions of Office.
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Upload your XLS spreadsheet
Drag and drop XLS files created in Excel 97-2003 or earlier. The converter reads the binary BIFF format including cell values, formulas, formatting, charts, and multiple worksheets.
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Select a modern format
Choose XLSX to upgrade to the modern Excel format with smaller file sizes, CSV for data extraction and database imports, PDF for printable output, or ODS for LibreOffice Calc compatibility.
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Download converted spreadsheet
Download your spreadsheet in a modern format that every current application supports. XLS to XLSX conversion preserves all data, formulas, and formatting while reducing file size.
Reasons to convert XLS Spreadsheets
XLS is a legacy binary format from Excel 97-2003. Convert to XLSX for smaller file sizes, better formula support, more rows and columns, and compatibility with current Excel features.
Convert XLS to CSV for importing data into databases, analytics tools, and modern applications. CSV eliminates binary format complexity and works with every data processing system.
Legacy XLS files may show formatting errors in modern Excel, Google Sheets, or Numbers. Converting to XLSX resolves rendering issues and means data displays correctly.
Convert XLS to PDF for clean, formatted printouts of spreadsheet data. PDF preserves column widths, cell borders, and number formatting across all printers.
Convert XLS to ODS for editing in LibreOffice Calc without a Microsoft Office license. ODS preserves cell data, formulas, and basic formatting in an open-standard format.
The XLS binary BIFF format risks becoming unreadable. Convert to XLSX or CSV to future-proof your spreadsheet data for long-term access and compliance.
Convert XLS documents online, no desktop apps, no plugins. No watermarks added, formatting preserved, and files are deleted from our servers within 1 hour.
About the XLS Format
XLS is the legacy spreadsheet format used by Microsoft Excel from version 97 through 2003. It stores data in the Binary Interchange File Format (BIFF), a proprietary binary structure that encodes cell values, formulas, formatting, charts, and macros. XLS files are limited to 65,536 rows and 256 columns per worksheet compared to the million-plus rows in modern XLSX.
Despite being superseded by XLSX, XLS files remain common in legacy enterprise systems, government agencies, and archived business data. The format supports VBA macros, embedded objects, and multiple worksheets. XLS files can be opened in modern Excel, Google Sheets, LibreOffice Calc, and most spreadsheet applications, though converting to XLSX is recommended for better performance, larger data capacity, and improved security.