Documents

XLS → XLSX

Learn about the formats: What is XLSX?

Convert legacy Microsoft Excel XLS spreadsheets to the modern XLSX format instantly. This tool is essential for users upgrading from older Office versions to ensure full compatibility with modern spreadsheet applications.

XLS is the older binary file format used primarily by Microsoft Excel 97-2003, whereas XLSX is an XML-based open standard introduced with Excel 2007. When converting an XLS document to XLSX, the underlying data structure is repackaged into a compressed archive of XML files. This transition allows your spreadsheet to take advantage of modern features, larger grid limits of 1,048,576 rows by 16,384 columns, and better integration with web-based office suites.

The conversion between these two document formats happens entirely without data loss, meaning all formulas, cell values, and formatting remain completely intact.

Tips

Check your macro-enabled files; standard XLSX does not support VBA macros (use XLSM if macros are present).
Verify that charts and conditional formatting render correctly after moving from the old binary structure.
Take advantage of the smaller, optimized XML file structure once the conversion is complete.

Common use cases

Opening legacy accounting sheets from older business archives in modern versions of Microsoft Office or Google Sheets.
Updating historical corporate reporting documents to comply with contemporary IT standards.
Preparing old spreadsheet datasets for automated processing pipelines that exclusively accept XML-based XLSX inputs.

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