Convert XLS → XLSX Online — Free
Upgrade old Excel .xls files to modern .xlsx format.
Drag & drop or click to browse
Accepts .xls files up to 30 MB
Free plan includes 5 conversions/day. Need more? Talk to us →
What is a .xls file?
XLS is a widely-used format in the Spreadsheet category. Upgrade old Excel .xls files to modern .xlsx format. Files in this format are commonly used across various tools, pipelines, and workflows.
What is a .xlsx file?
XLSX is a popular format in the Spreadsheet ecosystem. Converting from XLS to XLSX gives you access to its unique features, broader tooling support, and improved interoperability.
How to convert XLS → XLSX online
Upload your file
Drag & drop your .XLS file onto the upload zone, or click "Browse" to select it.
Validate & preview
The tool checks the file type and size before uploading. Invalid files are rejected immediately with a clear error.
Convert on the server
Click "Convert" to upload and process your file. Server-side conversion typically takes ~15 seconds.
Download your result
When done, click "Download .XLSX" to save your converted file. Files are securely deleted after 1 hour.
Frequently asked questions
Is this XLS to XLSX converter free?
Yes. The XLS → XLSX tool is free for up to 5 conversions per day. Pro (50/day) and Business (unlimited) plans unlock higher limits.
Is my file secure on the server?
Your file is uploaded over an encrypted HTTPS connection to a secure server worker. The converted file is stored temporarily and automatically deleted after 1 hour. We never share or store your files longer than necessary.
What is the maximum file size for XLS?
You can convert files up to 30 MB. If your file is larger, consider compressing it first or upgrading to a Business plan for increased limits.
What is the difference between XLS and XLSX?
XLS and XLSX are both formats in the Spreadsheet category, each with different use cases, tooling support, and feature sets. Upgrade old Excel .xls files to modern .xlsx format.
Can I convert multiple files at once?
Batch conversion is available on Pro and Business plans. Free users convert one file at a time.