Convert XLS to XLSX
Convert XLS files to XLSX locally, completely free and with maximum privacy.
Drag and drop your files here
or click to browse local files (large files supported, limited only by browser RAM)
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How to convert XLS to XLSX
- Drop your .xls files above, or click Upload Files. You can add many files at once.
- XLSX is already selected as the output. Open the settings (gear icon) to fine-tune the result.
- Click Convert All. SheetJS runs inside your browser through WebAssembly; nothing is uploaded.
- Download your .xlsx files as soon as each one finishes.
What to know about XLS to XLSX conversion
- Cell values, formulas, number formats and sheet names carry over; cell styling (colors, fonts, borders), charts and macros are not preserved.
- XLSX is best for everyday spreadsheets shared with Excel users, and opens in Excel, Google Sheets, LibreOffice and Numbers.
XLS vs XLSX
| Feature | XLS (Excel 97-2003 Workbook) | XLSX (Excel Workbook) |
|---|---|---|
| Multiple sheets | Yes | Yes |
| Formulas and formatting | Yes | Yes |
| Best for | compatibility with Excel 97–2003 and legacy systems | everyday spreadsheets shared with Excel users |
| Opens in | Excel, LibreOffice and Google Sheets | Excel, Google Sheets, LibreOffice and Numbers |
XLS (Excel 97-2003 Workbook): The legacy binary Microsoft Excel format (BIFF8), still common in older systems.
XLSX (Excel Workbook): The default Microsoft Excel workbook format since Office 2007, based on Office Open XML.
Conversion options
- Active sheet only or all sheets
- Custom output file name
Frequently asked questions
Is it safe to convert XLS to XLSX here?
Yes. Your files are processed entirely on your own device by WebAssembly code running in the browser. They are never uploaded, so nobody else can see them, and the converter keeps working even if your connection drops after the page loads.
Is there a file size limit?
There is no server-side limit. The only limit is the memory available to your browser, typically 1.5–4 GB on desktop computers.
Can I convert several XLS files at once?
Yes. Add as many files as you like; they are converted in parallel according to your device's CPU cores, and you can apply the same settings to all of them.
Related conversions
Need the opposite? Convert XLSX to XLS.
Convert XLS to other formats
Convert other formats to XLSX
See every XLS converter and XLSX converter, or browse the full converter directory.