DOCX vs ODT: Microsoft Word vs OpenDocument Format Compared

Two Open Standards, Two Ecosystems

DOCX and ODT are both open, standardized document formats. Both are ZIP archives containing XML. Both support rich text formatting, images, tables, styles, headers, footers, footnotes, and everything else you expect from a modern word processing format. On paper, they are nearly equivalent.

In practice, they serve different ecosystems. DOCX is the native format of Microsoft Word, the dominant word processor with roughly 80% market share in enterprise and education. ODT is the native format of LibreOffice and Apache OpenOffice, the leading free and open-source office suites. Google Docs supports both but uses its own internal format.

The choice between DOCX and ODT is less about which format is technically better (they are remarkably similar) and more about which ecosystem you and your collaborators operate in. Choosing the wrong format for your environment means friction: documents that need conversion, formatting that shifts between applications, and features that do not transfer cleanly.

This guide provides an honest, detailed comparison of the two formats across every dimension that matters in practice: compatibility, features, file structure, collaboration capabilities, tooling, and the political and organizational factors that influence format choice.

Technical Comparison

Aspect	DOCX (Office Open XML)	ODT (Open Document Format)
Standard	ECMA-376 / ISO 29500	OASIS ODF 1.3 / ISO/IEC 26300
Developed by	Microsoft (standardized via ECMA)	OASIS (community-driven)
File structure	ZIP with XML (document.xml, styles.xml, etc.)	ZIP with XML (content.xml, styles.xml, etc.)
Native editor	Microsoft Word	LibreOffice Writer, Apache OpenOffice Writer
Cross-editor support	LibreOffice, Google Docs, Pages, WPS Office	Microsoft Word (limited), Google Docs, Pages
Market share	Dominant (enterprise, education, general use)	Niche (open-source community, governments)
Font embedding	Supported	Supported (ODF 1.2+)
Macro language	VBA (Visual Basic for Applications)	LibreOffice Basic, Python, JavaScript
Change tracking	Full (sophisticated)	Supported (less feature-rich)
Comments	Threaded comments with replies	Comments (threading varies by version)
Drawing/shapes	DrawingML	SVG-based
Math equations	OMML (Office Math Markup Language)	MathML
Typical file size	Slightly larger	Slightly smaller

Architecture: Remarkably Similar

Both formats share the same fundamental architecture: a ZIP archive containing XML files for content, styles, metadata, and settings, plus a folder for embedded media (images, fonts). You can rename either file type to .zip and browse the internal structure with any archive tool.

The XML schemas differ, but the conceptual structure is parallel:

DOCX internal structure:

word/document.xml     (main content)
word/styles.xml       (style definitions)
word/settings.xml     (document settings)
word/media/           (images)
[Content_Types].xml   (file type declarations)

ODT internal structure:

content.xml           (main content)
styles.xml            (style definitions)
settings.xml          (document settings)
Pictures/             (images)
META-INF/manifest.xml (file type declarations)

The similarity is not a coincidence. Both formats were designed to solve the same problem (representing word processing documents in an open, portable way), and similar problems tend to produce similar solutions.

Compatibility: The Decisive Factor

This is where the comparison stops being theoretical and becomes practical. Compatibility with the people and systems you work with is the single most important factor in choosing a document format.

DOCX Compatibility

DOCX opens natively in:

• Microsoft Word (Windows, macOS, web, mobile) -- full, reference-quality support
• Google Docs -- very good support with some advanced feature limitations
• LibreOffice Writer -- good support, occasional rendering differences
• Apple Pages -- good support for basic documents
• WPS Office -- good support
• OnlyOffice -- good support

DOCX is the de facto standard. When someone says "send me a Word document," they mean DOCX. When a job application system accepts document uploads, it accepts DOCX. When a publisher specifies manuscript formatting, they specify Word. This ubiquity is DOCX's strongest advantage.

ODT Compatibility

ODT opens natively in:

• LibreOffice Writer -- full, reference-quality support
• Apache OpenOffice Writer -- full support
• Google Docs -- good support
• Microsoft Word (2007 SP2+) -- limited support with rendering differences
• Apple Pages -- basic support

ODT's compatibility is adequate but narrower. Microsoft Word can open ODT files, but the rendering is often imperfect -- styles may shift, spacing may differ, and advanced features may not transfer cleanly. This is partly because Word's ODF support, while functional, is not its primary development focus.

The Practical Reality

If you send a DOCX file to ten people, all ten will be able to open it and see essentially the same document. If you send an ODT file to ten people, most will be able to open it, but several may see formatting differences, and a few may not know what to do with it.

This compatibility gap is the primary reason DOCX dominates in practice, despite ODT being technically comparable. Format choice is a network effect: the format that most people use becomes the format that most people need, which makes more people use it.

Feature Comparison in Practice

Styles and Formatting

Both formats support named paragraph and character styles with inheritance. Both support all standard text formatting (bold, italic, underline, font selection, size, color), paragraph formatting (alignment, indentation, spacing), and page formatting (margins, orientation, headers, footers).

The differences are in the details:

DOCX separates "style formatting" from "direct formatting" in a way that makes it easy to apply a style and then override specific properties. Word's style system is deeply integrated with themes (coordinated color and font sets) and Quick Styles.

ODT uses a CSS-like style inheritance model that is conceptually elegant but can produce unexpected results when styles interact in complex documents. LibreOffice's style management is powerful but has a steeper learning curve than Word's.

Tables

Both formats handle tables comprehensively, but the implementations differ in how they calculate column widths, handle merged cells, and manage nested tables. These differences mean that the same table can look slightly different when opened in Word versus LibreOffice, even if the document was converted perfectly.

Math Equations

This is one of the clearest technical differences. DOCX uses OMML (Office Math Markup Language), Microsoft's proprietary equation format. ODT uses MathML, the W3C standard for mathematical notation on the web.

MathML is technically superior -- it is an open standard supported by web browsers, LaTeX tools, and accessibility technology. OMML is proprietary and only fully supported by Microsoft products. However, Word's equation editor is more polished and user-friendly than LibreOffice's Math editor for most users.

Converting equations between the formats is imperfect. Complex multi-line equations, matrix notation, and unusual mathematical symbols may not transfer cleanly between OMML and MathML. If your documents contain many equations, test the conversion with representative samples before committing to a cross-format workflow.

Macros

Macros are completely incompatible between the formats. DOCX uses VBA (Visual Basic for Applications); ODT uses LibreOffice Basic, Python, or JavaScript. A macro written for Word will not run in LibreOffice, and vice versa. If your documents rely on macros for functionality, you are locked into the corresponding editor and format.

Collaboration and Sharing

Real-Time Co-Authoring

DOCX: Microsoft Word supports real-time co-authoring through OneDrive and SharePoint. Multiple users can edit the same document simultaneously, with changes appearing in real-time and conflicts resolved automatically. Google Docs also supports DOCX co-editing through its cloud platform.

ODT: LibreOffice does not natively support real-time co-authoring in the way that Word + OneDrive does. Collaborative editing of ODT files typically uses a share-and-merge workflow (one person edits at a time) or a cloud platform like Collabora Online (the cloud version of LibreOffice). Google Docs supports ODT import/export but converts to its internal format for editing.

Track Changes

DOCX: Word's track changes system is the industry standard for document review. It captures every addition, deletion, and formatting change with author attribution and timestamps. The "Accept/Reject" workflow is intuitive and well-documented.

ODT: LibreOffice supports track changes with similar functionality to Word's. The feature works well within LibreOffice, but tracked changes in ODT files may not display correctly when opened in Word (and vice versa). Cross-format change tracking is an area of ongoing compatibility challenges.

Comments

DOCX: Word supports threaded comments with replies, making it possible to have multi-turn conversations anchored to specific document locations. Comments include author names, timestamps, and resolution status.

ODT: LibreOffice supports comments with author attribution and timestamps. Threaded replies were added in more recent versions of LibreOffice but may not transfer when converting between ODT and DOCX.

Government and Organizational Mandates

ODT Mandates

Several governments and public institutions have mandated or strongly recommended ODF (and thus ODT) for official documents:

• European Union: The EU has recommended ODF for interoperability across member states
• United Kingdom: The UK Government Digital Service selected ODF as the standard for government documents
• Brazil: The Brazilian government mandates ODF for all government documents
• India: India's government standards organization recommends ODF
• NATO: NATO has adopted ODF for some document exchange scenarios

These mandates are driven by the principle of technology independence -- governments do not want to be locked into a single vendor's format for their public records.

DOCX in Practice

Despite government ODF mandates, DOCX remains dominant in practice, even in organizations with official ODT policies. The reasons are pragmatic: Microsoft Office is deeply embedded in enterprise workflows, most external partners and citizens use Word, and the cost of training staff to use LibreOffice is often higher than the cost of Microsoft licenses.

The result is a common dual-format reality: organizations officially support ODT but actually use DOCX for most daily work, converting to ODT when required for compliance.

Converting Between Formats

DOCX to ODT

Open the DOCX file in LibreOffice Writer and save as ODF Text Document (.odt). LibreOffice is the best tool for this direction because it is the native ODT editor and understands the format completely.

ODT to DOCX

Open the ODT file in LibreOffice Writer and save as Microsoft Word 2007-365 (.docx). Again, LibreOffice is the best tool because it understands the source format natively. For a detailed guide on this conversion, see our article on how to convert ODT to DOCX.

Online Conversion

The document converter on ConvertIntoMP4 handles both conversion directions. Upload either format and download in the other. This is useful when you do not have LibreOffice installed or need a quick conversion on a mobile device.

Conversion Direction	Best Tool	Quality	Notes
DOCX to ODT	LibreOffice Writer	Good to excellent	Best for documents created in Word
ODT to DOCX	LibreOffice Writer	Good to excellent	Best for documents created in LibreOffice
Either direction (online)	Document converter	Good	No installation required
Either direction (batch)	LibreOffice headless	Good to excellent	Scriptable for large collections
Either to PDF	PDF converter	Excellent	Eliminates format compatibility issues

When to Convert to PDF Instead

If you are sending a document to someone who only needs to read it (not edit it), converting to PDF eliminates all format compatibility issues. PDF preserves the exact visual appearance regardless of the recipient's software, making it the safest option for external distribution. For more on this decision, see our PDF vs DOCX comparison.

Use the PDF converter to convert either DOCX or ODT to PDF, or see our guide on how to convert Word to PDF for detailed instructions.

Making the Choice

Choose DOCX If:

• Your organization uses Microsoft Office
• Your collaborators primarily use Word
• You need real-time co-authoring via OneDrive/SharePoint
• You are submitting documents to publishers, employers, or institutions that expect Word format
• You need to use VBA macros
• You want maximum compatibility with the widest range of recipients

Choose ODT If:

• Your organization uses LibreOffice or OpenOffice
• You value open standards and vendor independence
• You are in a government or institution that mandates ODF
• You work primarily on Linux
• You want a format with no vendor lock-in
• You do not need to share documents with Word users frequently

Choose Both If:

• You need to work with collaborators in both ecosystems
• Your organization officially supports ODF but practically uses DOCX
• You are migrating from one office suite to another

Choose PDF for Distribution:

Regardless of whether you work in DOCX or ODT, converting to PDF for final distribution eliminates all compatibility concerns. The document converter handles both DOCX-to-PDF and ODT-to-PDF conversions.

File Size Comparison

ODT files are typically 5-15% smaller than equivalent DOCX files. Both use ZIP compression, but ODT's XML schema tends to be slightly more compact. For practical purposes, the difference is negligible -- a 1 MB DOCX file might be a 900 KB ODT file, a difference that does not matter for email attachments, cloud storage, or any modern workflow.

For documents where file size genuinely matters, converting to PDF often produces the smallest file, especially when using PDF compression. See our guide on how to reduce PDF file size for compression strategies.

Frequently Asked Questions

Can I open ODT files in Word?

Yes, Microsoft Word 2007 SP2 and later can open ODT files. However, the rendering may differ from how the document appears in LibreOffice. Complex formatting, styles, and some features may not transfer perfectly.

Can I open DOCX files in LibreOffice?

Yes, and LibreOffice does a generally good job with DOCX files. Most standard documents open with correct formatting. Complex documents with advanced Word features (like SmartArt, Word-specific form controls, or complex VBA macros) may not render identically.

Which format is more "open"?

Both are ISO standards, but ODF has a longer history as an open standard and was designed by a multi-vendor consortium from the start. DOCX was developed by Microsoft and standardized after the fact. In terms of specification accessibility and implementation independence, ODF has a slight edge, though both specifications are publicly available.

Will my documents be readable in 20 years?

Both formats are ISO standards with publicly available specifications, which means they will remain readable as long as someone builds software that implements the specification. For maximum long-term readability, convert to PDF/A, which is specifically designed for indefinite preservation. See our PDF vs PDF/A guide for details.

Should I convert all my ODT files to DOCX (or vice versa)?

Only if you are permanently migrating to a different office suite. Keeping your files in their native format is always safest -- it avoids any formatting loss from conversion. Convert individual files as needed for sharing rather than batch-converting your entire archive.

Wrapping Up

DOCX and ODT are more alike than different. Both are open standards, both are technically capable, and both serve their respective ecosystems well. The choice between them is fundamentally a compatibility decision: which format works with the people and systems you interact with most?

For most people in most situations, DOCX is the pragmatic choice because of its ubiquity. For users committed to open-source software, government organizations with ODF mandates, and Linux users, ODT is the natural choice. And for many users, the answer is "both" -- working primarily in one format and converting as needed for the other.

Whatever you choose, the document converter makes moving between DOCX and ODT straightforward, and converting either to PDF via the PDF converter eliminates compatibility concerns entirely when you need to share documents with the outside world.