Free online XLSX to XLS converter

Convert modern Excel workbooks for older software that requires the XLS format.

Convert XLSX to XLS online - free

.xlsx .xls

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How to convert xlsx to xls file

August 18, 2026
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Older accounting systems, industrial software, and embedded office suites may accept only the legacy .xls format. Converting a modern workbook lets those applications open or edit the spreadsheet, although newer features may need adjustment.

What the XLSX format is

.xlsx is the default Microsoft Excel workbook format introduced with Excel 2007. It is an Office Open XML package: a ZIP archive containing XML files and related resources. Each worksheet can contain up to 1,048,576 rows and 16,384 columns. Microsoft Excel, Microsoft 365, LibreOffice Calc, Apple Numbers, Google Sheets, and many reporting systems can open or export XLSX workbooks.

What the XLS format is

.xls is Excel’s older binary BIFF workbook format, used mainly by Excel 97–2003 and software that supports the legacy Office format. Its main advantage is compatibility with older Windows applications, financial systems, industrial equipment, and embedded spreadsheet components. Each worksheet is limited to 65,536 rows and 256 columns, and the format lacks support for many features introduced after Excel 2003. XLSX files are often smaller because the package is compressed, so converting to XLS does not normally reduce file size.

How to convert the file

With Microsoft Excel

Open the .xlsx workbook.
Select File → Save As or press F12.
Choose a destination and set Save as type to Excel 97-2003 Workbook (*.xls).
Enter a filename with the .xls extension and select Save.
Review Excel’s compatibility warning and select Continue if the listed changes are acceptable.

With LibreOffice Calc

Open the workbook in Calc.
Select File → Save As.
Set the file type to Excel 97–2003 (*.xls) and keep automatic file-name extension enabled.
Select Save, then choose Use Excel 97–2003 Format when prompted.

With the 101convert online converter

For a conversion without installing desktop software, upload the workbook to the free converter on 101convert.com, select XLS as the output format, start the conversion, and download the resulting file. Avoid uploading confidential workbooks unless the service’s current privacy and retention terms meet your requirements.

For batch or automated conversion

LibreOffice can convert a workbook from a terminal when it is installed:

libreoffice --headless --convert-to xls --outdir output input.xlsx

The command writes the result to output. Use a separate output directory so the source is not overwritten, and quote paths containing spaces.

Compatibility limitations

Saving as XLS can remove or alter features that the binary format cannot represent, including some Excel tables, newer chart types, slicers, threaded comments, dynamic-array formulas, conditional formatting rules, external connections, and worksheet content beyond the XLS row or column limits. Formulas may be rewritten, unsupported formulas may become errors or values, and charts or layout elements may render differently.

After conversion, open the new file in the target application and verify formulas, charts, merged cells, print areas, page breaks, dates, data validation, filters, and non-Latin text. An .xlsx workbook cannot contain VBA macros; macro-enabled source workbooks normally use .xlsm. If a macro-enabled workbook is saved as .xls, its VBA project can be retained, but macro execution still depends on the receiving application’s security settings. A sheet exceeding 65,536 rows or 256 columns must be filtered or reorganized before it can be represented completely in XLS.

XLSX vs XLS: format comparison

How the XLSX and XLS formats compare on the properties that matter most for this conversion.

Comparison of the XLSX and XLS file formats
Property	.XLSX Microsoft Excel Open XML Spreadsheet	.XLS Microsoft Excel Spreadsheet
Editable text	No	No
Fixed page layout	No	No
Text formatting	Extensive	Extensive
Images	Yes	Limited
Interactive elements	Yes	Yes
Password protection	Basic	Basic
Opens in a web browser	Partial	Partial
Typical file size	Medium	Medium
Open standard	Yes	No
Best used for	Data exchange	Data exchange
Introduced	2007	1987
Developer	Microsoft	Microsoft
MIME type	application/vnd.openxmlformats-officedocument.spreadsheetml.sheet	application/vnd.ms-excel

Open XLSX file Open XLS file

Frequently asked questions

Is the XLSX to XLS converter free?

Yes, converting XLSX to XLS on 101convert.com is completely free. No registration, email address or installation is required.

How large can my XLSX file be?

You can upload XLSX files up to 1000 MB and convert up to 100 files at once in a single batch.

What happens to my uploaded files?

Files are processed automatically and deleted from our servers within a few minutes after conversion. We never view or share your files.

Do I need to install any software to convert XLSX to XLS?

No. The XLSX to XLS conversion runs entirely online in your browser and works on Windows, Mac, Linux, Android and iPhone.

Did the conversion fail?

In most cases, the cause is an incorrect file format. Please upload a valid XLSX file for this XLSX to XLS conversion. Occasionally, the issue may be on our side. We analyze recurring conversion failures and disable or fix the converter if we detect a defect.

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Additional formats for
xlsx file conversion

Reverse conversion

xls to xlsx

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