XLS to XLSX Converter
Upgrade an old Excel 97-2003 (XLS) workbook to the modern XLSX format.
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How to Convert XLS to XLSX Online
Converting XLS files to XLSX format is simple with PrivConvert. Our free online converter handles the entire process in your browser with no software installation required. Your files are processed securely in memory and never stored on our servers.
Drag and drop your file into the upload area, click to browse your device, or paste a URL to a file hosted online. You can upload files up to 250 MB and batch convert up to 20 files at once.
Once uploaded, the conversion from XLS to XLSX starts automatically. The process runs entirely in an isolated environment - your data never leaves the secure pipeline.
Your converted file is ready instantly. Click the download button to save it to your device. The file is deleted from memory immediately after download.
Why Choose PrivConvert?
Unlike other online converters that upload your files to remote servers, store them for days, and may use them for AI training or sell your data, PrivConvert was built with privacy as the foundation. Here's what makes us different:
Files are processed in volatile memory (RAM) and immediately purged. Nothing is ever written to disk or backed up.
All uploads and downloads are encrypted with TLS 1.3. Your files cannot be intercepted in transit.
Use any tool instantly without signing up, providing an email, or creating a profile. No tracking cookies, no user profiling.
Compatible with Windows, macOS, Linux, iOS, and Android. No plugins or desktop software needed - just a modern web browser.
XLS vs XLSX - Format Comparison
| Feature | XLS | XLSX |
|---|---|---|
| File extension | .xls | .xlsx |
| Supported by PrivConvert | Yes (as input) | Yes (as output) |
| Privacy-safe conversion | In-memory, zero storage | |
| Max file size | 250 MB per file | |
| Batch support | Up to 20 files simultaneously | |
Trusted by Thousands of Users
PrivConvert processes thousands of file conversions every day. Our commitment to privacy and security has made us the go-to choice for professionals, developers, and privacy-conscious users worldwide.