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
Convert your XLS files to XLSX format quickly and easily with BoltConverter. Our free online tool ensures your spreadsheets are updated to the modern Excel format without any software installation.
Enjoy fast, secure conversions. Your files are processed server-side and automatically deleted after conversion, protecting your data privacy. Get your converted file in moments.
Upload Your XLS File
Click the 'Upload File' button and select the XLS spreadsheet you want to convert.
Start Conversion
Once uploaded, click the 'Convert' button to begin the transformation to XLSX format.
Wait for Processing
BoltConverter will process your file on our secure servers, which usually takes only a few seconds.
Download XLSX File
After conversion, click the 'Download' button to save your new XLSX file to your device.
Frequently asked questions
Is BoltConverter's XLS to XLSX tool free to use?
Yes, BoltConverter offers this XLS to XLSX conversion tool completely free of charge for all users.
How long does BoltConverter store my files?
Your files are processed server-side and are automatically deleted from our servers immediately after the conversion is complete. We do not store your data.
Is there a file size limit for XLS to XLSX conversions?
Yes, the maximum file size you can upload for conversion is 100 MB.
Will the converted XLSX file maintain the original quality and formatting?
Yes, BoltConverter is designed to preserve the original data, formatting, and structure of your XLS file during the conversion to XLSX.
Can I convert multiple XLS files to XLSX at the same time?
Currently, BoltConverter processes one XLS file at a time for conversion to XLSX. Please convert your files individually.