DOCX vs ODT vs RTF: Which Document Format to Use

The three formats at a glance

Format	Standard	Inside the file	Key year
DOCX (.docx)	ECMA-376, ISO/IEC 29500	ZIP of XML parts	2006, first Ecma standard (20 years ago)
ODT (.odt)	OASIS ODF, ISO/IEC 26300	ZIP of XML parts	2011, ODF 1.2 published (15 years ago)
RTF (.rtf)	Microsoft specification 1.9.1	Plain text with control words	2008, last release (18 years ago)

DOCX and ODT are modern, XML-based and maintained by standards bodies. RTF is a frozen format from one company. All three hold editable text with formatting, which is what sets them apart from a PDF.

DOCX: Office Open XML

DOCX is the word processing part of Office Open XML. The Library of Congress describes it as a ZIP-based package, built on the Open Packaging Conventions, whose main content is marked up in an XML vocabulary called WordprocessingML. It has been the default format for new documents in Microsoft Word since Word 2007.

Ecma International first standardized it in 2006 as ECMA-376, now in its 5th edition from December 2021, in 4 parts. It was approved as ISO/IEC 29500 in 2008, 18 years ago. The standard has two variants. Transitional, the one in everyday use, keeps legacy markup for compatibility with older Word files; Strict disallows it. In 2017 tests reported by the Library of Congress, Google Docs and LibreOffice also created new documents in the Transitional variant.

ODT: OpenDocument Text

ODT is the text document format of the Open Document Format (ODF), developed by a technical committee at OASIS. ODF 1.2, published in 2011, is the same text as ISO/IEC 26300-1:2015, and OASIS has since published ODF 1.3. An ODT file is also a ZIP package; the Library of Congress says it contains at least 5 files: mimetype, content.xml, styles.xml, meta.xml, settings.xml.

LibreOffice uses ODF 1.2 as its native format, and Microsoft has supported ODF 1.2 since Office 2013. So a Word user can open and save ODT, and a LibreOffice user can open and save DOCX. The question is what changes on the way.

RTF: Rich Text Format

RTF is a Microsoft format. An RTF file is plain text, usually 7-bit ASCII, made of control words, control symbols and groups in braces, so you can open it in a text editor and read the markup. The last version, 1.9.1, was published in March 2008, 18 years ago, and the Library of Congress says the format is no longer enhanced with new features.

That age shows. According to the Library of Congress, features added in Word 2010 and later are lost when a document is saved as RTF, RTF does not support alt text for images, and it has no built-in encryption. It rates RTF as acceptable for its collections but below XML-based formats and PDF/A. It also notes that RTF files cannot be opened in Word Online or in the Word apps for tablets.

What survives DOCX to ODT

Microsoft's support page for current versions of Word says data and content convert, but formatting and how you interact with some features can differ. Its feature list for saving a .docx as .odt:

Word feature	In the .odt file
Track changes	Not kept; all changes are accepted
Comments	Kept, but tables inside comments are lost
Content controls	Converted to plain text, except drop-down lists in newer Word
Bibliography	Converted to plain text
SmartArt	Becomes a group of shapes
Nested text boxes	Shapes or text boxes inside a text box are lost
Charts	Kept, converted to a group
Tables	Over 64 columns not supported; theme styling becomes cell formatting
Footnotes	Kept; custom separators are not
Equations	Kept
Document protection	Removed
Macros	Not supported

The tracked-changes row matters most: if you send a draft as ODT from Word, every pending change is accepted. Microsoft also notes that .odt files with document protection cannot be opened. Before converting, accept or reject changes yourself, and keep the DOCX original.

Old .doc files first

Before DOCX became the default in Word 2007, Word saved new documents in the binary .doc format. The Library of Congress says that converting a .doc file to DOCX in Word is designed to have 100 percent fidelity. So if you have an old .doc that needs to go to ODT or RTF, move it to DOCX in Word first, check it, and convert that copy. Going from Word to ODT is a different trip: the Library of Congress notes that Office 2013 and later export ODF 1.2, but without change tracking, which matches the first row of the table above. The order of conversions matters less than keeping the original file untouched at every step.

Round trips and fonts

The Library of Congress is blunt about conversion between DOCX and ODF: the two formats use different underlying models, and a round trip to an identical document should never be expected. Themes are a known problem, because ODF has no equivalent concept. It also notes that a document can display differently after conversion from a format with different markup, and when the original fonts are not installed. RTF adds its own losses on top. As general guidance, every conversion is a chance for spacing, page breaks, numbering and images to shift, so check the result page by page if the layout matters.

When to send a PDF instead

Editable formats are for documents the reader will change. When the reader only needs to read, print, sign or file the document, a PDF keeps the layout as you saw it. The Word to PDF converter turns a DOCX into a PDF in the browser. What changes on that trip, and on the way back, is covered in PDF vs DOCX: what changes.

Send DOCX to Word users who will edit or comment.
Send ODT to LibreOffice users, or when a process asks for an open standard format.
Send RTF only for simple text, and only when the reader asks for it.
Send PDF for final versions, forms to print and anything where the layout must not move.

If you receive a PDF and need to edit it, PDF to Word rebuilds an editable DOCX, and PDF to text pulls out only the words when formatting does not matter.

Before you convert

Accept or reject tracked changes, and resolve comments with tables in them.
Remove document protection or expect it to be dropped.
Use fonts the reader is likely to have, or send a PDF.
Keep the original file; convert a copy.
Open the converted file and compare it with the original before sending.

Frequently asked questions

What is the difference between DOCX and ODT?

Both are ZIP packages of XML files and both are international standards. DOCX is Office Open XML, standardized as ECMA-376 and ISO/IEC 29500, and has been the default in Microsoft Word since Word 2007. ODT is the OpenDocument text format from OASIS, standardized as ISO/IEC 26300, and is the native format of LibreOffice.

Is RTF still used?

Word can still save as RTF, but the Library of Congress notes that the format is no longer enhanced: version 1.9.1 from March 2008 is the last release. Features added in Word 2010 and later are lost when you save as RTF, and RTF does not support alt text for images.

Does Word open ODT files?

Yes. Microsoft has supported ODF 1.2 since Office 2013, and Word can save as .odt. Microsoft says content converts but formatting may differ, and lists features such as track changes and document protection that are not kept in .odt.

Will a document look the same after converting DOCX to ODT and back?

Not exactly. The Library of Congress says the two formats use different underlying models and that a round trip to an identical document should never be expected. Themes are a known gap because ODF has no equivalent concept.

Which format should I use to send a document?

If the reader will edit it, send the format their software saves natively, usually DOCX for Word users and ODT for LibreOffice users. If the layout must stay fixed or the reader only needs to read, print or sign it, a PDF is the safer choice.

Sources

Written by Tobias. Updated November 2, 2026.