FileChange

DOC vs DOCX

DOC and DOCX are both Microsoft Word document formats, but they are built on completely different technologies. DOC is the original binary format used by Word from 1997 through 2003 -- a single opaque file that stores text, formatting, and objects in a proprietary structure. DOCX, the default since Word 2007, is an Open XML format: a ZIP archive containing readable XML files, one for the text, others for styles, images, and settings. This modern structure makes DOCX smaller, more resistant to corruption, easier for other software to read, and a documented open standard rather than a closed binary blob. For almost everyone, DOCX is the better format. DOC remains relevant only when working with very old documents or software that predates 2007.

DOC vs DOCX — Feature Comparison

Feature	DOC	DOCX
File Structure	Binary (proprietary blob)	ZIP of XML files (Open XML)
File Size	Larger	Smaller (compressed XML)
Open Standard	Proprietary	ECMA-376 / ISO standard
Corruption Recovery	Hard (one binary file)	Easier (separate XML parts)
Editability	Full in Word	Full in Word and modern editors
Third-Party Support	Limited / reverse-engineered	Wide (documented schema)
Word Compatibility	Word 97 and later	Word 2007 and later
Macro Storage	Macros embedded in file	Macro-free (.docm holds macros)
Modern Features	No SmartArt, limited XML	SmartArt, content controls, full XML
Default in Word	Legacy (manual choice)	Default since 2007

When to use DOC

Use DOC only when you must work with truly legacy environments -- Word 2003 or earlier, or older business systems and document workflows that were never updated to read Open XML. DOC is also what you receive when opening archived files from the late 1990s and early 2000s. In these cases, keep the file as DOC for compatibility, but consider converting a working copy to DOCX for everyday editing and safer long-term storage.

When to use DOCX

Use DOCX for essentially all modern document work: writing, sharing, collaboration, and archiving. It is the default in every current version of Word, opens cleanly in Google Docs, LibreOffice, Pages, and countless other tools, and produces smaller, more durable files. The open XML structure means a single damaged image or section is far less likely to destroy the entire document. For any new document you create today, DOCX is the correct choice.

Verdict: DOC vs DOCX

DOCX is the better format in nearly every way -- smaller files, an open documented standard, broader software support, and far easier corruption recovery. Use DOCX for all new documents. Keep DOC only for genuine legacy compatibility, and convert old DOC files to DOCX when you need to edit or preserve them long-term.

DOC vs DOCX — Frequently Asked Questions

What is the actual difference between DOC and DOCX?

DOC is Word's old binary format -- a single proprietary file. DOCX is an Open XML format: a ZIP archive of XML files. You can literally rename a .docx to .zip and open it to see the XML parts inside. This structure makes DOCX smaller, more open, and easier to recover when damaged.

Can older versions of Word open DOCX?

Word 2007 and later open DOCX natively. Word 2003 and earlier need the free Microsoft Office Compatibility Pack to open DOCX files. Without it, older Word can only open DOC. This is the main reason DOC still circulates in some organizations.

Is DOCX smaller than DOC?

Yes. DOCX stores its XML content in a compressed ZIP container, so the same document is typically smaller as DOCX than as DOC. The savings are most noticeable in text-heavy documents; files dominated by large embedded images compress less either way.

Does converting DOC to DOCX lose any formatting?

For most documents, conversion preserves text, styles, tables, and images faithfully. Very old or complex DOC files with legacy macros or unusual field codes may need minor cleanup. Always keep the original DOC until you have confirmed the converted DOCX looks correct.

Should I save new documents as DOC or DOCX?

Save as DOCX. It is the modern default, produces smaller and more durable files, and is supported by virtually every current word processor. Only choose DOC if a specific recipient or system explicitly requires the older format.