Convert XLS to XLSX Online
XLS and XLSX serve different purposes. Convert XLS to XLSX here when you need data analysis, budgets, reporting.
How to convert XLS to XLSX
- Upload your XLS file. Drag it onto the box above or click to browse. Files up to 200 MB are accepted.
- Choose XLSX as the output. The target format is pre-selected on this page — just press “Convert now”.
- Download the result. Conversion runs on our own server and the download starts as soon as it is ready. Your files are deleted automatically.
Why convert XLS to XLSX?
XLS is the legacy binary Excel spreadsheet format. XLSX is the modern Excel workbook format. That difference is exactly why converting between them is so common: XLSX is the better choice for data analysis, budgets, reporting.
XLS vs XLSX: key differences
| XLS | XLSX | |
|---|---|---|
| File type | legacy | editable |
| Typical use | legacy spreadsheets | data analysis, budgets, reporting |
| Compatibility | Superseded by XLSX. | Supported by Excel, Google Sheets and LibreOffice. |
Tips for a clean XLS to XLSX conversion
- Superseded by XLSX.
- Use the highest-quality source XLS you have — converting a compressed file again cannot restore lost detail.
- If you only need a smaller file, try a lower resolution or bitrate instead of a different format.
- Keep the original XLS until you have checked the converted XLSX opens the way you expect.
Frequently asked questions
How do I convert XLS to XLSX?
Upload your XLS file to the converter on this page, make sure XLSX is selected as the output format and click “Convert now”. When the conversion finishes the download starts automatically.
Is this XLS to XLSX converter free?
Yes — it is completely free and needs no account. Files up to 200 MB are accepted, and heavy use is rate-limited so the service stays available for everyone.
Will converting XLS to XLSX reduce quality?
Because both formats preserve the original data, converting back and forth does not degrade quality.
What is a XLS file?
XLS is the legacy binary Excel spreadsheet format. Its technical name is Microsoft Excel 97-2003 and it is typically used for legacy spreadsheets.
What is a XLSX file?
XLSX is the modern Excel workbook format. Its technical name is Office Open XML Spreadsheet and it is typically used for data analysis, budgets, reporting.
Can I convert XLS to XLSX on my phone?
Yes. The converter runs in the browser on Android, iOS, Windows, macOS and Linux — no app installation is required.
Are my files kept on the server?
No. Uploaded files and converted results are deleted automatically a short time after the conversion finishes.