Convert modern XLSX files to legacy XLS format for compatibility with older Excel versions
Accepted formats: .xlsx
Size up to 50MB
Files deleted automatically
Secure upload (SSL)
Convert your Excel files in 3 simple steps. It's fast, secure, and free!
Drag & drop your .xlsx file or click to browse. Max size 50MB
Click on 'Convert' and wait for your file to finish converting.
The converted file will be automatically downloaded in your browser
We convert XLSX to XLS using LibreOffice, a trusted open-source office suite. It produces consistent results - like opening and saving the file in a real spreadsheet app, but fully automated.
XLS is the classic Excel format. We preserve your data, sheets, and most formatting, and we keep charts and images when possible. Some newer XLSX-only features may be simplified because the XLS format has older limits.
No installation and no account required. Convert files up to 50MB, and we automatically clean up temporary files after the conversion.
The classic XLS format has strict worksheet limits: 65,536 rows and 256 columns per sheet.
If your XLSX file exceeds these boundaries, our converter will automatically trim each sheet to fit within the XLS limits. Any rows beyond row 65,536 and columns beyond column 256 will be omitted in the resulting XLS file.
For files that stay within the limits, all data and formatting are preserved perfectly. If you need to keep all rows and columns, consider splitting large sheets or using the modern XLSX format.
A simple overview of the features and benefits of the formats
XLS Format is the classic Microsoft Excel spreadsheet file (versions 97-2003). Data is stored in numbered cells forming rows and columns. It supports static data, complex mathematical formulas, chart-building, and macros (Visual Basic). XLS is widely compatible with most spreadsheet software.
XLSX Format is the modern Microsoft Excel spreadsheet standard used since 2007. Based on the Office Open XML format, it uses ZIP compression to make file sizes much smaller than XLS. It efficiently stores plain text, complex formulas, and graphics in cells, but it does not support macros (for macros, the usual format is XLSM).
It's tempting to think of XLS as a relic, but plenty of critical systems still run on it — tax authorities, hospital databases, logistics software, and financial institutions often require XLS uploads because their backend was built decades ago and never updated. Converting XLSX to XLS isn't about going backwards; it's about speaking the language your recipient's system actually understands. Just be aware of the trade-offs before you convert: the 65,536-row limit, the 256-column cap, and the fact that features like sparklines, certain pivot table options, and modern conditional formatting simply don't exist in the old format.
Sometimes the oldest format is the safest bet — converting XLSX to XLS is what you do when a bank, government portal, or 20-year-old ERP system refuses to accept anything but the classic .xls file.
Short answers about XLSX to XLS conversion, formatting, and file security
Our engine is optimized for heavy data. You can comfortably upload and convert spreadsheet files up to 50MB without performance drops or freezes.
On average, the process of converting XLSX to XLS takes no more than 10 minutes with a light server load.
Yes. The converter perfectly retains your original layout, including custom cell formatting, borders, colors, and complex formulas during the XLSX to XLS conversion process.
Absolutely. All file transfers use end-to-end SSL encryption. Your files are processed automatically and are permanently deleted from our servers after conversion.
Yes, it is completely free. There are no hidden fees or subscriptions.
No registration required. You can start converting files immediately.
Convert to XLS for compatibility with older Excel versions (2003 and earlier) and legacy systems that don't support XLSX.
XLS is the older binary format used by Excel 97-2003. XLSX is the modern XML-based format introduced in Excel 2007 with better compression and higher limits.
While our online tool is great for quick tasks, our Desktop Version offers pro features for power users.