Convert CSV to XLSX
Convert CSV 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 CSV to XLSX
- Drop your .csv 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 CSV to XLSX conversion
- Numbers and dates are detected automatically, and accented characters are kept intact (UTF-8).
- XLSX is best for everyday spreadsheets shared with Excel users, and opens in Excel, Google Sheets, LibreOffice and Numbers.
CSV vs XLSX
| Feature | CSV (Comma-Separated Values) | XLSX (Excel Workbook) |
|---|---|---|
| Multiple sheets | No | Yes |
| Formulas and formatting | No | Yes |
| Best for | importing data into databases, CRMs and apps | everyday spreadsheets shared with Excel users |
| Opens in | any spreadsheet, database or text editor | Excel, Google Sheets, LibreOffice and Numbers |
CSV (Comma-Separated Values): A plain-text tabular format where each line is a row and values are separated by commas.
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 CSV 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 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 XLSX to CSV.
Convert CSV to other formats
Convert other formats to XLSX
See every CSV converter and XLSX converter, or browse the full converter directory.