Convert your XLS files to XLSX instantly online. Free, fast, and secure — no signup required.
Convert XLS to XLSX Free →No software to install. Works in your browser on any device.
Click "Choose File" or drag and drop your XLS file onto the converter. Up to 50 MB free.
FlipFiles will detect your file type automatically. Click the .XLSX format button to select it.
Hit Convert and download your XLSX file in seconds. No watermarks, no registration needed.
Understanding your file formats helps you choose the right conversion.
The older Microsoft Excel format, compatible with all versions of Excel and most spreadsheet software.
Microsoft Excel's modern format and the industry standard for spreadsheets, data analysis, and reporting.
Everything you need to know about converting XLS to XLSX.
Yes, completely free. You get 3 free conversions per session with no account required. Create a free account to save your history, or upgrade for unlimited conversions.
Most XLS to XLSX conversions complete in under 10 seconds. Larger files may take slightly longer depending on your internet connection and file size.
Yes. All uploaded files are processed on our secure servers and automatically deleted within 10 minutes of conversion. We never store or share your files.
Quality depends on the output settings. FlipFiles uses optimized defaults to preserve the best quality for XLSX files.
Yes! FlipFiles works in any browser on mobile, tablet, or desktop. No app download required.
Join thousands of users who convert files with FlipFiles every day. No account needed to get started.
Start Converting →Need a different format? We've got you covered.