CSV to XLSX converter
To convert CSV to XLSX, drop your CSV file in the box below. It converts straight away; press Download to save the XLSX. It all happens in your browser, so your file stays on your device.
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Converted on this device, never uploaded
What changes
| CSV to XLSX | What happens |
|---|---|
| Numbers | Stored as numbers; 007, +46 and 15+ digit IDs stay text, so no digit is lost |
| Dates | ISO dates (2026-03-02) become real Excel dates |
| Header | The first row in bold and frozen while you scroll |
| Delimiter | Comma, semicolon, tab or pipe, found automatically |
| Encoding | UTF-8, UTF-16 or Windows-1252: accents come out right in Excel |
How to convert CSV to XLSX
- Add your CSV. Drop the file in the box, or click to choose it. It becomes XLSX straight away.
- Check the result. Look at the preview. The delimiter and value types are set for you; change them if needed.
- Download. Press Download to save the XLSX.
Why XLSX
Make a real Excel workbook from a CSV, so numbers add up, dates sort as dates and nothing is mangled on opening.
Questions
Excel guesses: it drops leading zeros (007 becomes 7), turns long IDs into 1.23E+15 and reads some codes as dates. The XLSX made here keeps each value as written.
Yes. Switch off “Numbers and true/false as values”.
Up to Excel’s own limit of 1,048,576 rows.
No. The conversion happens right in your browser, so your file stays on your device. There is no account to make, either.