Convert XLS to XLSX
Turn an older Excel spreadsheet (.xls) into the modern XLSX format — ready for current Excel versions and tools that no longer support the legacy binary format.
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Why Convert XLS to XLSX?
XLS is Excel's older binary format from Excel 97-2003, which modern versions of Excel and many newer tools have deprecated or dropped active support for.
XLSX, introduced in Excel 2007, is the current standard — smaller file sizes, better recovery from corruption, and the format most current spreadsheet tools expect by default.
Because XLS predates two decades of spreadsheet feature changes, files with older macros, unusual formatting, or legacy features can occasionally need a closer look after conversion — a real factor in why this pair's success rate is lower than more modern-to-modern conversions.
How to Convert XLS to XLSX
- Upload your .xls file.
- MiConvert converts the legacy binary format to modern XLSX structure.
- Download the converted XLSX file.
- Open in current Excel versions, and re-verify any old macros.
Key Features of MiConvert XLS to XLSX
- Converts legacy Excel XLS files to the modern XLSX format
- Preserves standard formulas, formatting, and cell styles
- No Microsoft Excel installation required
- Compatible with current Excel versions and modern spreadsheet tools
- Free for files up to 50MB, 100MB for registered accounts
Video Tutorial
Watch this step-by-step tutorial to learn how to convert XLS files to XLSX format online for free using MiConvert.com. No software installation required.
Frequently Asked Questions
Will my formulas and data convert correctly?
Standard formulas and data convert reliably. Very old macros (VBA from Excel 97-2003) may need to be re-verified, since macro-security handling has changed significantly since XLS was current.
Why did my XLS to XLSX conversion fail?
Corrupted or unusually old XLS files (especially those from Excel versions predating 97) are the most common cause — files saved from Excel 97-2003 in standard condition convert reliably.
Will formatting and cell styles be preserved?
Yes, for standard formatting — colors, fonts, borders, and cell styles carry over correctly for the vast majority of spreadsheets.
Do I need Excel installed to convert?
No — the conversion happens entirely on our servers.
How do I change XLS to XLSX without opening the file?
This converter does exactly that — upload the .xls and download an .xlsx without ever opening it in Excel. The whole conversion runs on our servers, which is handy for batch-upgrading old spreadsheets or when you don't have Excel installed.
Is XLS the same as XLSX?
No. XLS is Excel's older binary format from Excel 97-2003, while XLSX is the XML-based format introduced in Excel 2007. XLSX files are typically smaller, recover better from corruption, and are the default that modern spreadsheet tools expect — which is why upgrading legacy XLS files is often necessary.
Is there a file size limit?
50MB free, 100MB for registered accounts.