XLS vs XLSX: Which Excel Workbook Format Should You Use?
XLS is the older binary Excel format; XLSX is the modern Open XML workbook format.
XLS is the older binary Excel format; XLSX is the modern Open XML workbook format. This guide explains the practical choices before using xls.now.
What the conversion changes
Conversion translates the source into a different storage and presentation model. Pay particular attention to compatibility, capacity, recoverability, and file size. Keep the original XLS file as the editable or authoritative copy.
Recommended workflow
- Open the XLS TO XLSX converter.
- Upload a valid source file and wait for it to finish transferring.
- Run the conversion and download the result.
- Open the new file in its intended application and compare it with the source.
Quality checklist
Review formulas, dates, merged cells, print areas, hidden sheets, charts, and number formats after conversion.
Test a representative file before processing a larger batch. If exact editability matters, retain both the source and converted result.
Privacy and reliability
xls.now uses HTTPS uploads and automatic retention controls. Do not upload a damaged or incorrectly named file; a filename extension alone does not repair its internal structure.
Common questions
Will conversion preserve everything?
Supported content is preserved where the destination has an equivalent. Features without a direct equivalent can be flattened, omitted, or represented differently.
Should I delete the original?
No. Keep the source until you have inspected the output and confirmed it meets the intended workflow.