About the XLS to XLSX
Upgrade old Excel 97-2003 (.xls) and OpenDocument (.ods) spreadsheets to modern .xlsx files that open everywhere. Spreadsheets often hold customer lists, finances or personal data, so FileStripe converts them in your browser instead of on a server.
Formulas are converted to their last calculated values, and formatting such as colours and fonts isn't carried over to CSV or JSON.
How to convert XLS to XLSX
- Add your file (or several).
- Conversion starts automatically.
- Download the converted files or a ZIP.
Features
- XLSX, XLS, ODS, CSVOld and new formats.
- All sheetsEach sheet exported separately.
- BatchMany files at once.
- PrivateData stays on your device.
Frequently asked questions
Why do accents look wrong when I open the CSV in Excel?
Keep 'Excel-friendly encoding' ticked: it adds a marker that tells Excel the file is UTF-8.
Which delimiter should I use?
Comma for most software. If you're in a country that uses a comma as the decimal separator (most of Europe), Excel expects semicolons.
Is the XLS to XLSX free?
Yes. The XLS to XLSX is completely free with no sign-up, no watermarks, no daily limits and no premium tier.
Are my files uploaded to a server?
No. FileStripe processes your files locally in your web browser using JavaScript. Nothing is uploaded, so the XLS to XLSX is safe for private photos and confidential documents and even works offline once the page has loaded.
Does it work on iPhone and Android?
Yes. The XLS to XLSX works in Safari, Chrome, Firefox, Edge and Samsung Internet on phones, tablets and computers. On a phone you can pick files from your photo library or files app and share the result straight to another app.
Last updated · Processing happens locally in your browser.