Convert XLS to XLSB
Convert XLS files to XLSB 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 XLSB
- Drop your .xls files above, or click Upload Files. You can add many files at once.
- XLSB 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 .xlsb files as soon as each one finishes.
What to know about XLS to XLSB conversion
- Cell values, number formats and sheet names carry over. Formulas are saved as their last calculated values in XLSB, and cell styling, charts and macros are not preserved.
- XLSB is best for very large Excel workbooks that must open fast, and opens in Excel and LibreOffice.
XLS vs XLSB
| Feature | XLS (Excel 97-2003 Workbook) | XLSB (Excel Binary Workbook) |
|---|---|---|
| Multiple sheets | Yes | Yes |
| Formulas and formatting | Yes | Yes |
| Best for | compatibility with Excel 97–2003 and legacy systems | very large Excel workbooks that must open fast |
| Opens in | Excel, LibreOffice and Google Sheets | Excel and LibreOffice |
XLS (Excel 97-2003 Workbook): The legacy binary Microsoft Excel format (BIFF8), still common in older systems.
XLSB (Excel Binary Workbook): A binary Excel format that loads and saves large workbooks faster than XLSX.
Conversion options
- Active sheet only or all sheets
- Custom output file name
Frequently asked questions
Is it safe to convert XLS to XLSB 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 XLSB to XLS.
Convert XLS to other formats
Convert other formats to XLSB
See every XLS converter and XLSB converter, or browse the full converter directory.