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XLS to XLSX

Convert old binary Excel XLS files to the modern XLSX format. XLSX has been the default Excel format since Office 2007 — it is smaller, more reliable, and better supported across all platforms. In-browser conversion with SheetJS. No signup required.

Updated June 2026

  1. 1Upload your XLS file
  2. 2Conversion runs instantly
  3. 3Download your XLSX file

Drop your XLS file anywhere, click to browse

Excel 97-2003 · Converted XLSX downloads automatically

Ctrl+Vto paste a copied file

How to use XLS to XLSX

  1. 1

    Upload your XLS file

    Drag and drop your XLS file into the upload area, or click to browse and select it from your device. Nothing is sent to a server.

  2. 2

    Conversion runs instantly

    ToolBubble converts the file to XLSX directly in your browser — no waiting in an upload queue.

  3. 3

    Download your XLSX file

    Once processing finishes, the converted XLSX file downloads automatically to your device.

Frequently asked questions

Everything you need to know about xls to xlsx.

XLS is the legacy binary Excel format used in Excel 97-2003. XLSX is the modern XML-based format introduced in Excel 2007. XLSX files are typically 30-75% smaller and are better supported in all modern applications.

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