Convert your .xls files to .xlsx format online for free. No software to install. Fast, secure, and easy.
Free — 3 conversions per day
Drag and drop your .xls file or click to browse.
Select XLSX as your output format.
Click Convert and download your .xlsx file.
Converting from XLS (Microsoft Excel Binary Spreadsheet) to XLSX (Office Open XML Spreadsheet) helps you work with your content in a different application or workflow. XLS and XLSX serve different purposes, and converting between them bridges the gap.
XLS (Microsoft Excel Binary Spreadsheet, introduced in 1987) uses None (OLE2 compound binary) compression. XLSX (Office Open XML Spreadsheet, introduced in 2007) uses ZIP (containing XML parts) compression. XLS browser support: None (requires office application). XLSX browser support: None (requires office application or online viewer).
The quality impact depends on the specific settings used during conversion. XLSX uses compression that may affect quality depending on the chosen settings.
Typical XLS file size: A 10,000-row spreadsheet: ~1-5 MB. Typical XLSX file size: A 10,000-row spreadsheet with formulas: ~500 KB - 2 MB. Expect a dramatic file size reduction — often 5-20x smaller — when converting from uncompressed XLS to XLSX.
For the best conversion results, always start from the highest quality source file available. Converting from a previously compressed file compounds any existing compression artifacts. When in doubt, use higher quality settings — you can always re-convert at lower quality later, but you cannot recover quality that has been lost.
Convert XLS to XLSX with 3 free conversions per day. No hidden fees.
Create a free account in 10 seconds and start converting immediately. No credit card required.
Files are encrypted during transfer, processed on secure servers, and deleted immediately after conversion.
Convert files from any device — desktop, tablet, or phone. No software to install, works in any modern browser.
SquishConvert supports over 358 file conversion combinations across images, documents, audio, and video.
Your converted .xlsx file maintains the best possible quality. No unnecessary compression or quality loss.
You get 3 free conversions per day. Upgrade to Pro for unlimited conversions.
Most files convert in under 10 seconds. Larger files may take a bit longer depending on size.
Yes. Files are encrypted during transfer, processed on secure servers, and deleted immediately after conversion. We never store your files.
Currently, SquishConvert converts one file at a time. Batch conversion is coming soon — stay tuned!
Free users can convert files up to 10 MB. Pro users can convert files up to 500 MB.