CSV to XLSX

Upload a CSV file and download it as XLSX. Free to start.

Drop files here, or press Enter to choose them. Up to 50 MB per file.
Drop a CSV file hereFree · up to 50 MB · 10 operations in total without an account · or paste with Ctrl+V
  • Sent over HTTPS · link expires in 24 h

How it works

  1. Step 1:

    Drop the CSV file on the orange block above, or press “Choose CSV”.

  2. Step 2:

    Press “Convert to XLSX”. The block shows the progress while the server converts the file.

  3. Step 3:

    Press “Download” to save the XLSX file. On Free the link works for 24 hours.

How CSV to XLSX conversion works

Converting CSV to XLSX imports comma-separated plain text into an Excel spreadsheet, adding the formatting, column structure, and formula capabilities that CSV cannot store. CSV contains raw tabular data as plain text with one record per line and field values delimited by commas; XLSX stores cells in an XML-based structure with defined column widths, number formatting, and optionally applied styles. During import, the converter detects column data types (numbers, dates, and text) and assigns the appropriate cell format in the XLSX output. Columns containing date strings in ISO 8601 or locale-specific formats are converted to Excel date serial numbers with a date display format applied. Leading zeros in fields such as postal codes are preserved only if the column is formatted as text. 1converter uses LibreOffice Calc in headless mode to perform this conversion, applying auto-detection of delimiter characters (comma, semicolon, or tab) and UTF-8 encoding for the input CSV.

Sources and specifications

When to convert

What the XLSX file is good for and why people convert to it.

  • Preserves tabular structure in a worksheet grid instead of raw comma-delimited text
  • Enables column typing (numbers/dates) for cleaner sorting and filtering in Excel
  • Turn exported CSV from a database or API into an Excel workbook for reporting
  • Import survey or inventory CSV and then filter, sort, and build pivots in XLSX

Where your file goes

  • It travels to our server over an encrypted HTTPS connection and is converted there.
  • The XLSX file comes back as a private link. It stops working after 24 hours on Free and 7 days on paid plans, and then the files are deleted.

Questions and answers

What people ask before converting CSV to XLSX.

Ask supportAll questions
Does CSV to XLSX keep all the data exactly as in the CSV?
Yes, the rows and columns are transferred into worksheet cells. If your CSV has quoted fields or special characters, proper parsing ensures they land in the correct cells in XLSX.
Will numbers and dates stay numeric in the XLSX file?
The converter can map CSV text to Excel cell types so numbers and dates behave correctly for sorting and formulas. If a column is ambiguous (e.g., mixed formats), Excel may still treat it as text.
Is XLSX larger than CSV?
Often yes: CSV is plain text with no styling, while XLSX is a zipped XML workbook that includes worksheet structure and metadata. The XLSX size typically grows with added formatting and multiple sheets.
Can XLSX be opened in Excel even if the original CSV had no formatting?
Yes. Even though CSV has no formatting, XLSX will open as a standard workbook with cells laid out in a grid, and you can apply formatting afterward in Excel.

More about this pair

Many files at once? Starter converts 5 at a time, 100 a day.

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