Convert CSV to XLSX
Turn a CSV file into a real Excel spreadsheet. Delimiter and character set are detected, and the file never leaves your browser.
Drag a CSV file hereChoose CSV file
One CSV or text file up to 50 MB. Delimiter and character set are detected automatically.
Processed on your device, no upload
Paste text instead of choosing a file
Guide and details
How it works
- Choose a CSV file or drop it onto the area above. Or paste the text.
- Check in the preview that columns and special characters were recognised correctly.
- If needed, open the advanced settings: delimiter, header row, sheet name, numbers and dates.
- Choose “Create XLSX” and download the file.
Text stays text, numbers only on request
By default the tool stores every value as text. That keeps postcodes with a leading zero, long account numbers and article numbers unchanged. If you want real numbers or dates, you can turn on a controlled detection. It converts only clear cases such as 12.5 or 2024-03-05. Numbers with leading zeros or more than 15 digits always stay text, because Excel would otherwise falsify them.
The result is a valid XLSX file, checked with independent programs such as LibreOffice and Python libraries.
Protection from formulas
A CSV file can contain cells that start with “=”, “+”, “-” or “@”. Excel could run them as formulas. The tool therefore stores such values as text, marked so that Excel does not run them. Real negative numbers such as -5 are untouched when you use number detection, and are otherwise text anyway.
Excel’s limits apply: at most 1,048,576 rows, 16,384 columns and 32,767 characters per cell. Files up to 50 MB are possible, less on smartphones. The tool does not create formatting, formulas or several sheets.
Frequently asked questions
Is my CSV file uploaded?
No. The file is read in your browser and the XLSX is created there.
How is the delimiter detected?
Automatically from the content (comma, semicolon, tab or pipe). You can also set it yourself in the advanced settings.
Why do numbers stay text?
That is the safe default so nothing is falsified. With number detection you turn clear numbers into real numbers.
What happens to cells that look like formulas?
They are stored as text so that Excel does not run them. The page tells you how many.
Can I read special characters from old files correctly?
Yes. If the file is not valid UTF-8, the tool reads it as Windows-1252. You can also choose the encoding yourself.