DevToolPal
EN

Excel to CSV Converter (XLSX ⇄ CSV)

Convert any sheet of an .xlsx workbook to CSV, or turn CSV into an Excel file. Dates, numbers and multi-line cells are kept. Nothing is uploaded.

Runs locally, never uploaded

Options

Excel file

CSV

What it does

This tool converts between Excel workbooks and CSV in both directions, entirely in your browser.

  • Excel → CSV: open an .xlsx file, pick a sheet, and get comma-separated (or semicolon, tab or pipe) text you can copy or download.
  • CSV → Excel: paste or open a CSV file and download a real .xlsx workbook with a bold, frozen header row and sensible column widths.

CSV is the simplest way to move table data between databases, scripts and apps, while Excel is what most people use to view and edit it. Switching between the two usually means opening a desktop app; here it takes a second and nothing leaves your computer.

How to use it

  1. Choose the direction under Convert.
  2. For Excel → CSV, click Open .xlsx… or drag a file onto the page. Every sheet is listed with its row and column count; click one to convert it. Workbooks can be up to 20 MB.
  3. Pick the separator. Comma is standard; many European versions of Excel expect semicolons.
  4. Copy the result or press Download. With several sheets, the file name includes the sheet name, and Download all sheets (ZIP) saves every sheet as its own CSV file (up to 100 sheets) using the same separator and BOM setting.
  5. For CSV → Excel, paste CSV into the editor or open a .csv file. The separator is detected automatically. Check the preview, then press Download .xlsx.

Click Sample to try either direction with a small order list.

How values are converted

Text, numbers and TRUE/FALSE values are copied as they are stored. Numbers are written with up to 15 significant digits, the same precision Excel shows, so 0.1 + 0.2 appears as 0.3. Dates and times are recognised from the cell’s number format and written in ISO 8601 form, which sorts correctly and imports cleanly into databases. Cells with line breaks, commas or quotes are quoted following RFC 4180, so the CSV opens back in Excel with the same cells.

Formulas are exported as their last calculated value. Merged cells keep their value in the top-left cell and leave the others empty. Formatting such as colours, fonts and number display rules (for example 75% or $1,200.00) is not part of CSV, so the plain stored value is written instead.

Example

An order sheet with a date column formatted as 2 March 2026 and a total calculated with =E2*F2 becomes:

Order ID,Date,Customer,Total
00123,2026-03-02,Acme Corp,59.7
00125,2026-03-09,"Smith, J.",6

Going the other way, the same CSV produces a workbook where Order ID stays as the text 00123 and Total is a number you can sum.

FAQ

› Is my spreadsheet uploaded?

No. The .xlsx file is unzipped and read by JavaScript in your browser, and the CSV or Excel file is created there too. Nothing is sent to a server, so confidential data stays on your device.

› Which Excel files can I open?

Workbooks saved as .xlsx or .xlsm by Excel 2007 or later, LibreOffice, Google Sheets, Numbers and similar apps. Old .xls files (Excel 97–2003) and password-protected workbooks cannot be read; open them in Excel and save as .xlsx first.

› How are dates and formulas converted?

Cells formatted as dates or times become ISO text such as 2026-03-02 or 2026-03-03 14:30:00, so every program reads them the same way. Formulas are written as the result Excel saved with the file, not as the formula itself.

› Why do Chinese or accented characters look wrong when I open the CSV in Excel?

Excel assumes an old local encoding for CSV files unless the file starts with a byte order mark (BOM). Keep the BOM option on and the downloaded CSV opens correctly in Excel; turn it off for tools that do not expect a BOM.

› Will CSV to Excel keep leading zeros like 00123?

Yes. Values with leading zeros, and numbers longer than 15 digits such as ID or card numbers, are stored as text so Excel does not change them. Other numbers are stored as real numbers so you can calculate with them.