Convert CSV to XLSX Online
Turn CSV files into Excel output online. The service is free, requires no account, supports batch queues, and limits server uploads to 100 MB per file. The conversion runs on the server in an isolated request. Keep the original file while you review the converted copy.
Convert .CSV to .XLSX
Select a file to begin. Processing details and limits are listed below.
How to convert CSV to XLSX
- 1
Add your CSV source
Add one or more CSV files to the queue. The uploader keeps batch items separate.
- 2
Set the Excel options
Set the available quality or format options, or keep the defaults for a first pass.
- 3
Create the Excel file
Run the queue and download the Excel files individually or together as a ZIP.
Comma-separated values vs Microsoft Excel Spreadsheet
| Spec | Comma-separated values | Microsoft Excel Spreadsheet |
|---|---|---|
| MIME type | text/csv | application/vnd.openxmlformats-officedocument.spreadsheetml.sheet |
| Format type | data | data |
| Standard | RFC 4180 | Pending review |
| First release | 2005 (RFC 4180); earlier usage predates the RFC | Pending review |
| Browser support | Text display and browser spreadsheet apps | Pending review |
| Contents | Plain-text rows and columns separated by a delimiter, usually commas, with optional quoting and a header row. | Structured spreadsheet with formulas. |
About Comma-separated values
Simple, human-readable, small, and supported by virtually every spreadsheet and database tool. No standard type system, delimiter and quoting conventions vary, and nested or hierarchical data does not fit naturally.
Format referenceAbout Microsoft Excel Spreadsheet
Structured spreadsheet with formulas.
Why convert CSV to XLSX?
- The output can simplify review because columns or objects match the destination tool's model.
- A format change can make the data readable to a non-technical reviewer.
- Converting a copy avoids changing the source export used by another process.
- Excel is a better fit for a spreadsheet, API, database import, or another tool in the data pipeline.
Will quality change?
The result is a new document, not a byte-for-byte copy. Keep the source for reference and print checks. Check a sample before processing a large batch.
Processing and limits
- Processing
- Server-side
- Engine
- LibreOffice and document tooling
- Maximum size
- 100 MB per file on the server.
- Batch support
- Yes, multiple files can be queued; completed results can be downloaded as a ZIP.
- Quality controls
- No quality slider. The output follows the fixed conversion path.
The file is processed on the server because the conversion requires a server-side engine or a utility operation.
- No standard type system, delimiter and quoting conventions vary, and nested or hierarchical data does not fit naturally.
- Check metadata, dimensions, and compatibility after the conversion.
- Very large files can hit the 100 MB server limit before conversion starts.
Platform compatibility
The output is a Excel file. Use an application or device that accepts that format, and test the result on the destination platform if compatibility is critical.
When not to convert
- Avoid repeated lossy conversions when quality matters; start from the highest-quality source available.
- If the file contains sensitive data, review the processing model before uploading it to a server.
- Do not convert when the original CSV must remain the only editable or archival copy.
Frequently asked questions
- What is the easiest way to convert CSV to Excel?
- Upload a CSV file, choose the available Excel options, run the conversion, and download the result. The tool is free, supports batches, and accepts server uploads up to 100 MB.
- Does Convert CSV to XLSX require an account?
- It is free, requires no account, and adds no watermark. Server uploads are limited to 100 MB per file, and browser-first paths are limited by device memory.
- What happens to quality?
- The result is a new document, not a byte-for-byte copy. Keep the source for reference and print checks. Check a sample before processing a large batch.
- Where is the file processed?
- Yes. This conversion uses a server-side engine, so the file is uploaded over HTTPS, processed in an isolated request, and removed after the result is produced.
- How do I process a batch?
- Queue multiple files, run them together, and download the finished results as a ZIP. Each server file is limited to 100 MB, and large batches may take longer.
- What can go wrong?
- Open the downloaded Excel file in the application or database you plan to use, check the structure against the source, and keep the original until the output is approved.