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XLS to XLSX Converter

Convert XLS files to XLSX in seconds, free and unlimited.

🔒 Files are processed on your device. Nothing is uploaded.

How to convert XLS to XLSX

  1. Click Choose files or drop your XLS files into the box. You can add several at once.
  2. Make sure XLSX is selected as the output format.
  3. Press Convert, then download your XLSX files.

XLS

Legacy Excel 97–2003 workbook.

XLSX

Microsoft Excel workbook, the default spreadsheet format since Office 2007.

Spreadsheets are converted with SheetJS. Formulas are kept as their calculated values; formats with a single table (CSV, HTML) export the first sheet.

Other XLS conversions

Convert other files to XLSX

FAQ

Is converting XLS to XLSX free?

Yes. Unlimited conversions, no sign-up, no watermark.

Are my files uploaded to a server?

No. FieldConvert processes files inside your browser, so your XLS files never leave your device. That makes it private and fast, because there is no upload or download wait.

Is there a file size limit?

Only your device's memory. Files up to about 2 GB work in most desktop browsers.