CSV to Excel Converter - Online Save as XLSX

CSV (Comma-Separated Values) is a plain-text format that stores tabular data with each line representing a row and values separated by delimiters like commas or semicolons. It contains no formatting, formulas, or multiple sheets.

XLSX (Excel Open XML Spreadsheet) is Microsoft's modern spreadsheet format. It supports multiple worksheets, cell formatting, formulas, charts, data validation, and more. XLSX files are ZIP-compressed XML archives, making them more efficient for complex data.

Converting CSV to XLSX allows you to leverage Excel's advanced features while maintaining better file structure and compatibility.

Absolutely. This tool processes all files entirely within your browser using client-side JavaScript. Your CSV data never leaves your device — it is not uploaded to any server, stored in any database, or accessible to anyone else. This approach, known as client-side processing, ensures maximum privacy and security. You can safely convert sensitive business data, financial records, or personal information without any privacy concerns.

Our converter automatically detects the most common delimiters used in CSV files:

• Comma (,) — Standard in US/UK and most English-speaking countries
• Semicolon (;) — Common in European countries where comma is used as decimal separator
• Tab (\\t) — Used in TSV (Tab-Separated Values) files
• Pipe (|) — Often used in legacy systems and database exports

You can also manually select the delimiter or enter a custom one if the auto-detection doesn't match your file's format. Preview the data to verify correct parsing before converting.

UTF-8 is the most common encoding and works for virtually all languages including special characters, emojis, and multilingual content. It's the default and recommended choice.

Other options include:

• UTF-16 LE/BE — Used by some Windows applications and legacy systems
• ISO-8859-1 (Latin-1) — Common in older Western European systems
• Windows-1252 — Default encoding for older Windows applications in English and Western European languages

If your CSV displays garbled characters or strange symbols in the preview, try switching to a different encoding that matches your file's origin.

Yes! Our tool supports CSV files up to 50 MB in size. The conversion happens entirely in your browser's memory, so performance depends on your device's resources. For files with hundreds of thousands of rows, the conversion may take a few seconds. We display a live row count after parsing so you can verify the data before downloading. For extremely large datasets (millions of rows), consider splitting the CSV into smaller chunks for optimal performance.

CSV files are plain-text and do not store formulas, formatting, or styling. When converting CSV to XLSX, the data values are preserved exactly as they appear in the CSV. Our tool offers two data handling modes:

• Auto-detect — Attempts to recognize numbers, dates, and boolean values, converting them to appropriate Excel cell types
• Keep as text — Preserves all values as plain text, which is useful for IDs, zip codes, and phone numbers that might otherwise be misinterpreted

If your original CSV contains formulas (which is unusual), they would appear as plain text strings in the XLSX output since CSV doesn't natively support formula storage.

The .xlsx files generated by this converter follow the Office Open XML standard and are compatible with:

• Microsoft Excel (2007 and later) — Windows and Mac
• Google Sheets — Upload and edit online
• LibreOffice Calc — Free and open-source spreadsheet software
• Apple Numbers — Native support for .xlsx files
• WPS Office and other office suites
• Online viewers like Microsoft 365 Online and Zoho Sheets

The output is a standard, universally accepted spreadsheet format that works across all major platforms.

No installation is required! This is a fully web-based tool that runs directly in your browser. There's nothing to download, install, or configure. It works on any modern browser including Chrome, Firefox, Safari, Edge, and Opera—on Windows, Mac, Linux, Android, and iOS. Simply visit the page, upload your CSV file, and download the converted XLSX. You don't even need an internet connection after the page has loaded, since all processing happens locally.