XLSX vs XLS: Modern and Legacy Excel Formats Compared
XLSX is an Open XML workbook; XLS is the older binary workbook format.
XLSX is an Open XML workbook; XLS is the older binary workbook format. This guide explains the practical choices before using xlsx.now.
What the conversion changes
Conversion translates the source into a different storage and presentation model. Pay particular attention to compatibility, row limits, features, and file size. Keep the original XLSX file as the editable or authoritative copy.
Recommended workflow
- Open the XLSX TO XLS 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, calculated values, dates, merged cells, print areas, hidden sheets, 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
xlsx.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.