1
Upload XLSChoose the XLS file you want to convert.
2
Review File
3
Convert to XLSX
4
Download XLSX
spreadsheet Converter• 100% Client-Side

XLS to XLSX Converter

Upgrade legacy binary XLS spreadsheets to modern XML workbooks.

xls→xlsx

Drop XLS file(s) here, or browse

Supports single or multiple batch conversion

Private by Design

Your files are processed directly on your device using WebAssembly, HTML5 Canvas, and client-side runtimes.

No server upload No cloud copy 100% local processing
How To Convert

How to Convert XLS to XLSX

Step 1

Upload XLS

Choose the XLS file you want to convert.

Step 2

Review File

Check the file information and conversion options.

Step 3

Convert to XLSX

Start the local XLS to XLSX conversion.

Step 4

Download XLSX

Download your converted XLSX file.

Frequently Asked Questions

Questions about XLS to XLSX Conversion

Is this a genuine XLSX conversion?

Yes, binary BIFF8 records are parsed and rebuilt as valid OpenXML.

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