How to convert CSV to XLSX
- Add your files. Drop CSV files anywhere on the page, or use Choose files. Folders and ZIP archives work too; every CSV inside is picked up.
- Check that XLSX is selected. XLSX is already chosen on this page. Other formats in the same row are one tap away if you change your mind.
- Adjust options if you need to. For workbooks with several sheets, choose every sheet or only the first.
- Convert and download. Press Convert. Each file shows its progress, then a Download button. With several files, “Download all” gives you a single ZIP.
What happens to your CSV
The CSV is read with SheetJS, the library behind many spreadsheet tools, and written as XLSX. All sheets are kept.
Cell values and sheet names are preserved. Formulas, cell formatting and charts may be simplified, especially when converting to or from older formats.
About CSV and XLSX
CSV: CSV is a plain-text table with commas between values. Every spreadsheet, database and analytics tool can import it.
XLSX: XLSX is the Microsoft Excel workbook format, which can hold several sheets, formulas and formatting.
Questions
Is my CSV file uploaded anywhere?
No. The conversion runs inside this browser tab using code served by this site, and the XLSX is created on your device. You can even disconnect from the internet once the page and its converter have loaded.
What happens to formulas and multiple sheets?
Formulas are saved as their calculated values. Multi-sheet workbooks keep every sheet in formats that support it; CSV, TSV, JSON and similar formats get one file per sheet, or a single object keyed by sheet name.
Can I convert several CSV files at once?
Yes. Drop as many CSV files as you like, a whole folder or a ZIP. They convert one after another, and “Download all” saves every XLSX in one ZIP that keeps your folder structure.
Is there a file size limit?
There is no fixed limit, because nothing is uploaded. The practical limit is your device’s memory: a phone may struggle with very large files that a laptop converts easily.