CSV to XLS converter
Convert CSV files to XLS with TLS uploads and automatic deletion. Legacy binary Microsoft Excel format, predating XLSX.
Drop a CSV file, or click to browse
Converts to XLS · runs live, right now
How it works
Drop your file
Drag a CSV file in, or click to browse. No account needed to try it.
We convert it
Secure upload, converted to XLS in our sheet pipeline.
Download the result
Grab your XLS file immediately, or find it later in your dashboard.
Why convert CSV to XLS?
Both CSV and XLS use no compression scheme of its own, so the conversion mainly changes compatibility, not quality. The main reason to convert CSV to XLS is compatibility: XLS opens cleanly in Excel, Google Sheets and most spreadsheet tools, while CSV doesn't always. If you're sharing a file with someone else, sending it to a tool that expects a specific format, or archiving it for the long term, XLS is usually the safer target.
Format comparison
| CSV | XLS | |
|---|---|---|
| Extension | .csv | .xls |
| MIME type | text/csv | application/vnd.ms-excel |
| Compression | no compression scheme of its own | no compression scheme of its own |
| Category | spreadsheet | spreadsheet |
Common reasons to convert CSV to XLS
- Importing data into a tool or script that only reads XLS
- Sharing a spreadsheet with someone who doesn't have CSV's original app
- Maximizing compatibility with older or stricter tools that expect an uncompressed XLS file
What actually happens to your file
SheetJS writes a BIFF8 .xls workbook (Excel 97-2003). CSV has no types, so everything lands as the values SheetJS infers — numbers that look like numbers, the rest as text. .xls has a 65,536-row / 256-column ceiling the newer .xlsx format doesn't; if you want modern Excel, convert to XLSX instead.
Your file, handled carefully
Uploads use TLS in transit and AES-256 SSE-S3 at rest in production (when the production S3 credential gate is enabled), are processed in an isolated job, and deleted on the schedule you choose — as fast as immediately. We don't index, search, or share files between accounts. Read the full security model →
Frequently asked questions
Is converting CSV to XLS free?
Yes — the Free plan includes 50 conversions every month, including CSV to XLS. Paid plans raise that limit.
Will I lose quality converting CSV to XLS?
XLS is legacy binary microsoft excel format, predating xlsx. We use the highest-quality encoder settings by default so visual or data loss is minimized.
Do you keep a copy of my file?
Files are deleted automatically based on your plan's retention options. Free accounts can keep results for 1h or 24h; Pro and above add options such as delete-immediately and 7 days.
What is CSV?
Comma-separated plain-text tabular data.
What happens if a conversion fails?
You get a clear error message and the job is marked failed in your history — we never silently drop a file. Retry is one click. Monthly quotas count attempts (including failures) because processing starts as soon as the job is created.