CSV to Excel (XLSX) Converter
Million-Row Support, No Upload

Convert CSV files to Excel (XLSX) format instantly in your browser. Dates, numbers, and text are automatically typed for Excel compatibility.

Drag & drop your file here, or browse

Accepts: .csv (up to 200 MB)

Max 10 million cells (rows × columns)

Your data stays in your browser. By using this tool, you agree to our Terms and Privacy Policy.

How to Convert CSV to Excel (Large File Support)

Drag and drop your CSV file onto the drop zone at the top of the page, or click to browse and select a file.

Conversion starts automatically. Dates and numbers are detected and converted to proper Excel types.

Click the "Download XLSX" button to save the Excel file.

Key Features of This CSV to Excel Converter

100% Local Processing: Your files are never uploaded to a server. All conversion happens in your browser using WebAssembly, so your sensitive data stays private.
Type-Aware Conversion: Dates become Excel date cells, numbers become numeric cells, and booleans are preserved. Formulas, sorting, and filtering work correctly from the start.
Free with No Limits: No row limits (up to Excel's 1,048,576 maximum), no file count restrictions, and no account required.

CSV vs Excel (XLSX): Differences and Benefits of Converting

CSV is a plain-text format where all values are strings. Excel (XLSX) is a rich binary format with typed cells, formatting, formulas, and multiple sheets.

	CSV	Excel (XLSX)
Data types	Everything is a string	Numbers, dates, booleans, text
Formatting	None	Cell styles, colors, borders
Formulas	Not supported	Full formula support
Multiple sheets	No	Yes
File size	Compact	Slightly larger (ZIP-compressed XML)
Compatibility	Universal	Excel, Google Sheets, LibreOffice

Benefits of Converting CSV to Excel

Open directly in Excel with correct data types — no more "number stored as text" warnings
Date columns are recognized as dates, enabling sorting, filtering, and date functions
Numeric columns support SUM, AVERAGE, and other formulas without manual conversion

Frequently Asked Questions

Is my data uploaded to a server?

No. Your file never leaves your browser. All processing happens locally using WebAssembly. No data is sent to any server.

Can I convert a large CSV file to Excel?

Yes, up to Excel's maximum of 1,048,576 rows. This tool uses DuckDB-WASM for fast in-browser processing. For files exceeding this row limit, consider using CSV to Parquet instead.

Are dates and numbers preserved correctly?

Yes. The converter detects DATE, TIMESTAMP, and numeric columns from your CSV. Date columns are formatted as Excel dates (yyyy-mm-dd), and numeric columns are stored as numbers, not text.

What is the file size limit?

The input limit is 200MB, with a maximum of 10 million cells (rows × columns). Since the XLSX workbook is built entirely in memory, large files may exceed browser memory limits.

What if my CSV has more than 1 million rows?

Excel supports a maximum of 1,048,576 rows per sheet. If your CSV exceeds this limit, the tool will show an error. For larger datasets, use CSV to Parquet for efficient columnar storage.

Does the tool handle different text encodings?

Yes. The tool automatically detects and converts text encodings including UTF-8, Shift-JIS, EUC-JP, Windows-1252, and more.