XLSX to XLS Converter

Convert XLSX to legacy XLS — fast and free online

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Backward Compatibility

Convert modern XLSX to the classic XLS format so your spreadsheets open in Excel 97–2003 and other legacy environments.

Instant Processing

Cloud servers handle the XLSX-to-XLS conversion in seconds — no waiting, no local software overhead on your machine.

Data Protection

Uploaded XLSX files are deleted immediately after conversion and output XLS files are purged within 24 hours.

How to convert XLSX to XLS

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose xls or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your xls file right afterwards

About formats

XLSX is the default spreadsheet format for Microsoft Excel since Office 2007, based on the Office Open XML (OOXML) standard published as ECMA-376 and adopted as ISO/IEC 29500. An XLSX file is a ZIP archive containing XML documents that describe workbook structure, sheet data, styles, shared strings, formulas, charts, pivot tables, and relationships between components. Each worksheet is stored as a separate XML part where cells are organized by row and column references with typed values and style indices. The XML foundation enables programmatic spreadsheet creation and manipulation using libraries like openpyxl (Python), Apache POI (Java), and ClosedXML (.NET) without requiring Excel. XLSX dramatically expanded capacity compared to XLS: over 1 million rows and 16,384 columns per sheet, enabling use cases previously impossible in the binary format. One advantage is openness and cross-platform support — the documented OOXML specification enables implementation by LibreOffice Calc, Google Sheets, Apple Numbers, and numerous specialized tools. Built-in ZIP compression is another practical strength: XLSX files are typically 50-75% smaller than equivalent XLS files, and the modular XML structure improves data recovery when files are partially corrupted. The format supports modern Excel features including structured tables, slicers, sparklines, Power Query connections, and real-time co-authoring. XLSX has become the standard format for spreadsheet data interchange across business, scientific, and government domains.
Developer: Microsoft
Initial release: January 30, 2007
XLS is the binary spreadsheet format of Microsoft Excel, first introduced with Excel 1.0 for Macintosh in September 1985 and becoming the dominant spreadsheet format worldwide. The format stores workbooks as OLE2 compound document files using the Binary Interchange File Format (BIFF), organizing sheets, cells, formulas, formatting, charts, pivot tables, macros, and metadata across multiple internal streams. Each cell record encodes the cell's value (number, string, boolean, error, or formula), position, and formatting index, while shared string tables and style records reduce redundancy. The format evolved through BIFF versions (BIFF2 through BIFF8), with BIFF8 (Excel 97) establishing the structure used through Excel 2003. XLS supports up to 65,536 rows and 256 columns per sheet, a limit that drove the creation of XLSX. One advantage is universal spreadsheet compatibility — XLS files are recognized by every major spreadsheet application including LibreOffice Calc, Google Sheets, Apple Numbers, and dozens of programming libraries across all platforms. The format's mature feature set is another strength: XLS handles complex formulas, conditional formatting, data validation, named ranges, array formulas, external references, and VBA macros. Although XLSX replaced XLS as the default in Office 2007, the binary format persists in financial institutions, legacy reporting systems, and any environment where Excel 97-2003 compatibility is required.
Developer: Microsoft
Initial release: September 1985

Frequently Asked Questions

Why convert XLSX to XLS?

XLS is required for older Excel versions (97–2003) and some legacy systems that cannot handle the newer XLSX format natively.

What apps open XLS?

Microsoft Excel (all versions), LibreOffice Calc, Google Sheets, WPS Office, and Apache OpenOffice Calc open XLS files.

Will macros carry over?

Standard cell data, formulas, and formatting transfer. VBA macros may need the XLSM format — XLS has limited macro support.

Is there a file-size difference?

XLS files are typically larger than XLSX because XLSX uses XML compression. Expect a modest size increase after conversion.

Can I batch-convert XLSX to XLS?

Yes — upload several XLSX files at once and Convertio converts them all to XLS in one go, saving you considerable time.

Is this service free to use?

Core conversions are free on Convertio. Premium tiers offer expanded limits for users who convert files frequently.

XLSX to XLS Quality Rating

4.7 (80,900 votes)
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