Compare
XLS vs XLSX
XLS is the older binary Excel workbook format, while XLSX is a spreadsheet format based on Office Open XML. Both can store formulas and formatting, but XLSX is the current choice for most modern Excel workflows.
Which format should you choose?
Keep XLS when maintaining legacy workbooks or compatibility requirements demand it; use XLSX for new workbooks and modern Excel-based sharing.
Good fit for XLS
Viewing and editing existing Excel workbooks
- Workbooks that specifically require XLS
Good fit for XLSX
Spreadsheet workbooks
- Formulas, formatting, and multiple sheets
Basic information
| Field | XLS | XLSX |
|---|---|---|
| Extension | .xls | .xlsx |
| MIME type | application/vnd.ms-excel | application/vnd.openxmlformats-officedocument.spreadsheetml.sheet |
| Common uses | Viewing and editing existing Excel workbooks | Spreadsheet workbooks |
| How to open | Open it in a compatible spreadsheet application and check formulas, formatting, charts, and external references. | Open it in a compatible spreadsheet application. Check formulas, displayed values, and formatting in the recipient's environment. |
| Export or convert | When converting to XLSX, check formulas, charts, print settings, and macros. | For simple exchange, export to CSV. Usually only values from one selected sheet are written, so keep formulas, formatting, other sheets, and charts separately. |
Choose by use case
Workbooks that specifically require XLS
Viewing and editing existing Excel workbooks
XLSFormulas, formatting, and multiple sheets
Spreadsheet workbooks
XLSXKey point 1
XLS uses an older binary workbook structure.
More on the differencesKey point 2
XLSX is a package containing XML parts and is the standard format in current Excel workflows.
More on the differencesMore on the differences
Use XLSX for new files unless a recipient or older system specifically requires XLS. After conversion, verify formulas, charts, macros, formatting, and external links; macro-enabled workbooks may require a different extension.
- Both formats can hold formulas and formatting, but their internal structures differ.
- XLSX is better aligned with current spreadsheet tools and supports larger worksheet limits than legacy XLS.
- Conversion can alter features or workbook behavior, so review important sheets after saving.
Frequently asked questions
Will converting XLS to XLSX preserve everything?
Not always. Check formulas, charts, macros, formatting, and links in the converted workbook and confirm the destination application supports them.