Convert CSV to XLS
Convert CSV files to XLS 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 CSV to XLS
- Drop your .csv files above, or click Upload Files. You can add many files at once.
- XLS 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 .xls files as soon as each one finishes.
What to know about CSV to XLS conversion
- Numbers and dates are detected automatically, and accented characters are kept intact (UTF-8).
- XLS is best for compatibility with Excel 97–2003 and legacy systems, and opens in Excel, LibreOffice and Google Sheets.
CSV vs XLS
| Feature | CSV (Comma-Separated Values) | XLS (Excel 97-2003 Workbook) |
|---|---|---|
| Multiple sheets | No | Yes |
| Formulas and formatting | No | Yes |
| Best for | importing data into databases, CRMs and apps | compatibility with Excel 97–2003 and legacy systems |
| Opens in | any spreadsheet, database or text editor | Excel, LibreOffice and Google Sheets |
CSV (Comma-Separated Values): A plain-text tabular format where each line is a row and values are separated by commas.
XLS (Excel 97-2003 Workbook): The legacy binary Microsoft Excel format (BIFF8), still common in older systems.
Conversion options
- Active sheet only or all sheets
- Custom output file name
Frequently asked questions
Is it safe to convert CSV to XLS 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 CSV 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 XLS to CSV.
Convert CSV to other formats
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See every CSV converter and XLS converter, or browse the full converter directory.