Convert XLS to XLSX, Free
Upload your XLS file and get a XLSX in seconds. No account, no watermark.
How to convert XLS to XLSX
XLS is the older Microsoft Excel binary format used by Excel 97 through Excel 2003. The newer XLSX format, introduced with Excel 2007, uses an open XML structure that is faster to open, less prone to corruption, and supported by all modern spreadsheet applications including Google Sheets and LibreOffice. Converting XLS to XLSX is recommended when working with older spreadsheet files.
BoltConverter converts your XLS file to XLSX on its servers. Formulas, cell formatting, multiple sheets, and charts are preserved in the output. The resulting XLSX file opens in any version of Excel from 2007 onward.
Upload your XLS file
Click the upload area or drag your .xls file onto the page.
Conversion runs on the server
The binary XLS file is converted to the XML-based XLSX format with all sheets and formulas preserved.
Download the XLSX file
Save the .xlsx file and open it in Excel 2007 or later, Google Sheets, or LibreOffice.
Frequently asked questions
What is the main difference between XLS and XLSX?
XLS is a binary format used by Excel 97-2003. XLSX is an XML-based open format introduced in Excel 2007. XLSX opens faster, has a smaller file size for comparable data, and is supported by more applications.
Will formulas and formatting be preserved?
Yes. Formulas, cell formatting, conditional formatting, and charts are all preserved in the XLSX output.
Can I open the XLSX in Google Sheets?
Yes. Google Sheets fully supports XLSX files. Upload it to Google Drive and open with Sheets.
Will macros (VBA) be included in the XLSX?
Standard XLSX does not support VBA macros. If your XLS file contains macros, they may be lost in conversion. Use the XLSM format (macro-enabled workbook) if you need to keep macros.
Is there a limit on the number of rows or sheets?
XLSX supports over 1 million rows per sheet and up to 255 sheets per workbook. XLS was limited to 65,536 rows. Very large XLS files exceeding these old limits cannot exist, so conversion should always succeed.