What is the difference between Excel XML and XLSX?

They are two different Microsoft spreadsheet formats. Excel XML - properly called SpreadsheetML , or the Excel 2003 XML Spreadsheet format - is the legacy plain-text XML format introduced with Excel 2002/2003, saved with a .xml extension. XLSX is the modern OOXML (Office Open XML) format that Excel 2007 and later use by default. This converter reads the legacy Excel XML spreadsheet and writes a modern OOXML .xlsx file that any current spreadsheet application opens natively.

How do I convert an Excel XML spreadsheet to XLSX?

Use our Excel XML Spreadsheet to XLSX Converter . Steps to convert an XML spreadsheet to XLSX: Upload the Excel XML file (or paste a URL) Click 'Run Conversion' button When the file is converted - download the .xlsx file

How do I know whether my file is an Excel 2003 XML spreadsheet?

Open the file in any text editor. If it begins with an XML declaration and contains a <Workbook> or <ss:Workbook> element, it is a SpreadsheetML file and this converter is the right tool. If instead you see your own data elements with no Excel-specific workbook wrapper, it is a generic XML data file - use the XML to Excel Converter instead, which maps XML data into spreadsheet rows and columns.

Are formulas and formatting preserved when converting XLS XML to XLSX?

Yes. Worksheet data across all sheets, cell formatting, number formats, merged cells, row heights and column widths carry over, and formulas remain live in the OOXML .xlsx output. The converted file behaves exactly like a spreadsheet saved by Excel itself.

Why convert SpreadsheetML to OOXML .xlsx at all?

The legacy Excel XML format stores everything as uncompressed plain text, so files are typically several times larger than the equivalent .xlsx. The modern OOXML .xlsx format is compressed, opens faster, and is accepted by Google Sheets, LibreOffice Calc and virtually every spreadsheet library and third-party tool, many of which do not read the older XML spreadsheet format at all.

Conversion Plan:

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Conversions:

Excel 2003 XML Spreadsheet (SpreadsheetML) to XLSX Converter

Online Converter: Convert a legacy Excel XML spreadsheet file (up to 1 GB) into the modern OOXML .xlsx format

Your XML file

Excel file format

XLSX (Excel 2007+)

XLS (Excel 97-2007)

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Convert legacy Excel XML spreadsheet files to the modern XLSX format for better compatibility, smaller file sizes, and improved performance. This converter handles the specific XML spreadsheet format that Excel itself saves, not generic XML data files.

A quick note on terminology, because the two formats are easy to mix up. The source format here is what Microsoft calls the Excel 2003 XML Spreadsheet, known technically as SpreadsheetML and often referred to as Excel XML or XLS XML. It is plain, uncompressed XML text saved with a .xml extension, and it was the interchange format of the Excel 2002 and 2003 era. The target format is .xlsx, the Office Open XML (OOXML) workbook format that Excel 2007 and every later version use by default. So this tool converts an Excel XML spreadsheet into a modern OOXML .xlsx workbook: same data, same formulas, same formatting, in the packaged format today's software expects.

Note: If you have a generic XML data file (not an Excel XML spreadsheet), use our XML to Excel converter instead.

When Do You Need This Converter?

Excel XML files (sometimes called SpreadsheetML) are a legacy format that some systems still generate. You might need to convert these files when:

Legacy System Exports: Older enterprise applications or reporting tools output data in Excel XML format rather than modern XLSX.
File Size Concerns: Excel XML files are uncompressed and can be 3-5x larger than equivalent XLSX files. Convert to reduce storage and transfer times.
Software Compatibility: While Excel opens XML files, some third-party tools and libraries only support the XLSX format.
Standardization: Convert legacy files to XLSX for consistent file management across your organization.
Email Attachments: XLSX files are smaller and more universally recognized than Excel XML files for sharing.

Understanding Excel XML Format

Microsoft Office XML (SpreadsheetML) is a native Excel format that stores spreadsheet data as human-readable XML text. Key characteristics:

File Extension: These files typically have a .xml extension but can be opened directly in Excel
Native Excel Format: Unlike generic XML, this format preserves Excel-specific features like formulas, formatting, and multiple sheets
Human-Readable: The XML structure can be viewed and edited in any text editor, useful for debugging or automated modifications
Uncompressed: Files are not compressed, resulting in larger sizes compared to XLSX but faster read/write for programmatic access

XLSX: The Modern Excel Standard

Office Open XML (OOXML), commonly known as XLSX, is the default format for Excel 2007 and later versions. Benefits of converting to XLSX:

Compressed Storage: XLSX is actually a ZIP archive containing XML files, resulting in significantly smaller file sizes
Universal Compatibility: Supported by Microsoft Excel, Google Sheets, LibreOffice Calc, and virtually all spreadsheet applications
Better Performance: Modern applications are optimized for XLSX, offering faster loading and processing times
Full Feature Support: XLSX supports all modern Excel features including advanced formatting, pivot tables, charts, and macros (as XLSM)

Format Resources

MS-XLSX - Excel file format specification (Microsoft)
Excel file formats - Supported formats (Microsoft)

How the Conversion Works

Our converter reads the Excel XML structure and recreates all content in XLSX format:

All worksheet data and multiple sheets are preserved
Cell formatting (fonts, colors, borders, number formats) transfers intact
Formulas are converted and remain functional in the XLSX output
Row heights, column widths, and merged cells are maintained
Named ranges and print settings carry over

Frequently Asked Questions

How do I know if my file is Excel XML?

Open the file in a text editor. If it starts with <?xml and contains <Workbook or <ss:Workbooktags, it's an Excel XML file. Regular XML data files won't have these Excel-specific elements.

What's the difference between this and the XML to Excel converter?

This converter handles Excel XML format (SpreadsheetML) - a native Excel format. The XML to Excel converter handles generic XML data files and maps them into spreadsheet rows and columns.

Will my formulas still work after conversion?

Yes, formulas are converted and will function in the XLSX output. The converted file works exactly like a native XLSX file created in Excel.

How much smaller will my file be?

XLSX files are typically 60-80% smaller than equivalent Excel XML files due to ZIP compression. A 10 MB Excel XML file might convert to a 2-3 MB XLSX file.

Is the conversion secure?

Yes. All uploads use encrypted HTTPS. Source files are deleted immediately after conversion, and results are removed within 24 hours.

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