File Converter Max File Size 256MB
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Convert XLS to XLSX
How to Convert XLS to XLSX?
Converting XLS to XLSX has always been easy using our converter. Here's how:
Step 1: Upload your file
Click the 'Upload' button to upload the XLS file you want to convert to XLSX.
Step 2: Step 2: Select the File Format
Select the file format to convert the files to. It must be an XLSX.
Step 3: Edit options
Now, you have multiple options like quality, resize etc, based on XLS and XLSX file format.
Step 4: Download Converted File
Once the conversion is complete, click the 'Download' button to save the converted XLSX file hassle-free!
XLS is the legacy Microsoft Excel binary format from the Office 97-2003 era. Converting XLS to XLSX modernises your spreadsheet files to the current Excel format, enabling more rows, better compression, and full compatibility with Excel 2007 and later features.
Our XLS to XLSX converter uses LibreOffice to open the binary .xls file and re-encode it as an Excel Open XML (XLSX) package. Worksheets, formulas, named ranges, and cell formatting are all preserved during the conversion.
XLSX files are XML-based and significantly more future-proof than the proprietary binary XLS format. They are smaller when compressed, easier to repair if corrupted, and supported natively by Excel, Google Sheets, LibreOffice, and Numbers.
XLS files are limited to 65,536 rows and 256 columns. After conversion to XLSX, these limits expand to 1,048,576 rows and 16,384 columns. If your data was at the XLS row limit, the conversion will not lose any rows — it simply unlocks a larger addressable space.