Skip to content
Expensico

CSV to Excel (XLSX) Converter

Convert CSV to a proper Excel XLSX workbook with numbers, dates as text and leading zeros preserved. Fast, private, in-browser.

Runs in your browser. Your files are processed on your device and are never uploaded.

How to use the CSV to Excel (XLSX) Converter

  1. Choose or drop your CSV file.
  2. Adjust the options if needed — the defaults work well for most files.
  3. Select Convert. Conversion happens instantly in your browser.
  4. Preview the result and download your Excel file.

About this CSV to Excel converter

Opening a CSV directly in Excel can mangle data: leading zeros vanish from PIN codes and phone numbers, long IDs turn into scientific notation, and Unicode text can appear garbled. Converting to XLSX here avoids those problems because each cell's type is set deliberately.

How CSV to Excel conversion works

  1. The CSV is parsed in your browser with automatic delimiter detection.
  2. Plain numbers become numeric cells. Values with leading zeros, more than 15 digits or a leading + are stored as text so they are never altered.
  3. A standard .xlsx workbook is generated locally, with column widths sized to fit the data.

Conversion quality: Exact. All rows and columns are written to a single Excel sheet; numbers stay numeric.

When to convert CSV to Excel

  • Sharing data with colleagues who work in Excel
  • Preserving IDs, account numbers and PIN codes exactly
  • Adding formatting or formulas to exported data

Limitations to be aware of

  • CSV has no formatting, so the workbook uses default styling.
  • Dates are kept as text to avoid regional misinterpretation (e.g. 03/04 as March or April).

CSV vs Excel

CSV. CSV (comma-separated values) stores a table as plain text, one row per line. It is supported by almost every spreadsheet, database and programming language, but it has no formatting, formulas or multiple sheets.

Excel (XLSX). XLSX is the default Microsoft Excel workbook format since Excel 2007. It can hold multiple sheets, formulas, formatting and charts.

This converter also accepts TSV files as input.

Frequently asked questions

Why not just open the CSV in Excel?

Excel guesses data types when opening CSV and can permanently drop leading zeros or round long numbers. Converting first keeps your data intact.

Will it work with Google Sheets and LibreOffice?

Yes. XLSX is supported by Google Sheets, LibreOffice Calc, Numbers and Excel.

Are my files uploaded?

No. This tool reads and processes files directly in your web browser. Nothing is sent to Expensico's servers, and the data is discarded when you close or reload the page.