Question 1

How do I convert XLS to XLSX without uploading files to a server?

Accepted Answer

Fileora converts XLS (XLS) directly inside your web browser using WebAssembly. Drop your XLS file into the converter box above, confirm XLSX as the output, and click Convert. Your file data stays in local memory on your device.

Question 2

Is converting XLS to XLSX on Fileora private?

Accepted Answer

Yes. Standard cloud converters transfer your files over the network to external machines. Fileora executes all decoding and encoding locally in your browser. Nothing is sent to an external server or saved remotely.

Question 3

What is the expected quality of this XLS to XLSX conversion?

Accepted Answer

The fidelity rating for this conversion is EXACT. Layout and core formatting are preserved with high fidelity.

Question 4

When should I choose XLSX over XLS?

Accepted Answer

XLS is typically used for Reading legacy corporate financial archives and historical reports., while XLSX works best for Financial modeling, business analytics, multi-tab accounting, and charting.. Switching to XLSX provides broader compatibility across readers and modern devices.

Property	XLS	XLSX
Category	spreadsheet	spreadsheet
File Extension	.xls	.xlsx
MIME Type	application/vnd.ms-excel	application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
Common Apps	Microsoft Excel, LibreOffice Calc	Microsoft Excel, Google Sheets
Best For	Reading legacy corporate financial archives and historical reports.	Financial modeling, business analytics, multi-tab accounting, and charting.

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