Convert CSV to XLSX

Convert CSV to XLSX instantly in your browser. Your spreadsheet data is processed on your device and never uploaded.

Your file never leaves your device.

How to convert CSV to XLSX

XLSX opens natively in Excel, Google Sheets, Numbers and LibreOffice with typed columns, widths and multiple sheets. This tool reads the CSV with SheetJS, a proven spreadsheet engine, directly in your browser and writes a correct XLSX file with the right encoding, escaping and structure. There are no rows to copy by hand and no data leaves your computer.

Step 1: Choose your CSV file
Drag and drop a .csv file onto the converter or click to browse. It works on desktop, tablet and phone.
Step 2: Automatic conversion
Rows and columns are read and written as XLSX in a fraction of a second.
Step 3: Download the XLSX
Save each result individually, or download everything as a single ZIP when you convert several files.

Good to know

Numbers and dates are detected automatically, so they arrive as real numeric cells instead of text.
UTF-8 text, accents and emoji are preserved.

Why use this CSV to XLSX converter?

XLSX opens natively in Excel, Google Sheets, Numbers and LibreOffice with typed columns, widths and multiple sheets.
Handles large files with thousands of rows.
Correct quoting and UTF-8 encoding.
100% local: spreadsheets often contain personal or financial data, and here it never leaves your device.

Is it free?

Yes. Converting CSV to XLSX is free, with no watermark, signup or email required. Local conversions have no artificial file-size or daily cap; the practical limit is your device.

Is my file uploaded?

The CSV file is processed entirely in your browser. It is never uploaded, never stored and never seen by anyone, so this is safe for confidential files.

About the formats

What is CSV?

CSV (comma-separated values) is a plain-text format that stores tabular data, one row per line and fields separated by commas. It needs no special software: any text editor, spreadsheet application or database can read it. Because of its simplicity, CSV is the universal interchange format between databases, spreadsheets and other programs.

Use CSV whenever you need to move tabular data between systems, exporting a database, importing contacts or sharing a table with someone who uses different software. Choose CSV when plain, predictable data matters more than formatting.

CSV (Comma-Separated Values)

What is XLSX?

XLSX (Excel Open XML) is the standard spreadsheet format from Microsoft Excel, also supported by Google Sheets and LibreOffice Calc. Data is organised into cells and sheets, with support for formulas, functions, charts and formatting. Because the file is a ZIP container of XML, its content stays readable and easy to process.

Use XLSX for tabular data that needs structure and calculation, budgets, inventories, lists and anything with formulas or multiple sheets. When you only need the raw data, you can export a single sheet to CSV or JSON here.

Excel Spreadsheet (XLSX)

Frequently Asked Questions

Is CSV to XLSX conversion free?

Yes. It is free, with no watermark, signup or email required. Local conversions have no artificial file-size or daily cap; the practical limit is your device.

What happens to formulas when converting CSV to XLSX?

The calculated values are exported. The formulas themselves are not part of the output format.

Is it safe to convert csv to xlsx here?

Yes. The work happens on your own device with WebAssembly and browser APIs, so the file is not uploaded at all. You can even disconnect from the internet once the page has loaded.

Do I need to install anything?

No. Everything runs in a modern browser (Chrome, Edge, Firefox or Safari) on Windows, macOS, Linux, Android and iOS. There is no app, plugin or account.

Can I convert XLSX back to CSV?

Yes, there is a dedicated XLSX to CSV converter linked in the related tools below. Keep in mind that information dropped in one direction cannot always be restored in the other.

Need the opposite? Convert XLSX to CSV Online

ExcelProcessed locally