CSVLark

CSV viewer, cleaner & converters

Convert

Excel to CSV

Open an .xlsx workbook, pick a sheet and save it as CSV or TSV. Dates come out in ISO format and numbers without floating-point noise, and the workbook never leaves your computer.

Excel workbook

Drop an .xlsx file here
or

No workbook open.

Options

Open an .xlsx workbook to get started.

Sheet preview

CSV

How to convert Excel to CSV

  1. Drop an .xlsx file on the box or click Open .xlsx file. No workbook to hand? Sample workbook builds one with two sheets.
  2. Choose the sheet. The preview and the CSV text update straight away.
  3. Pick the delimiter and line endings your next tool expects, then copy or download the CSV, or download every sheet as one ZIP file.

What to expect

  • Values, not formulas. The last value Excel calculated is exported for formula cells.
  • Dates in ISO format (2026-10-27, or 2026-10-27 14:30:00 with a time), whatever display format the cell used.
  • Clean numbers. Binary rounding noise is removed, so 0.1 + 0.2 is written as 0.3, as Excel displays it.
  • TRUE and FALSE for boolean cells, as in Excel's own CSV export.

Workbooks are read with the open-source read-excel-file library, which loads only when you open a file.

Frequently asked questions

Does it support old .xls files?

No, only .xlsx files (Excel 2007 and later; LibreOffice, Numbers and Google Sheets can save them too). Open an .xls file in a spreadsheet program and save it as .xlsx first.

What happens to formulas and formatting?

Each cell's last calculated value is exported, as with Excel's own Save as CSV. Formatting, colors, comments and charts are not part of a CSV file, so they are left out.

How are dates written?

Cells formatted as dates are written as YYYY-MM-DD, plus HH:MM:SS when they have a time. ISO dates sort correctly and import cleanly into databases and scripts.

Should I add a byte order mark?

Add it if the CSV will be opened in Excel and contains accented or non-Latin characters: the BOM tells Excel the file is UTF-8. Leave it off for databases and scripts.