DOC vs EPUB
A detailed comparison of Word Document (Legacy) and EPUB eBook — file size, quality, compatibility, and which format to choose for your workflow.
Word Document (Legacy)
Documents & TextDOC is the legacy binary format used by Microsoft Word 97-2003. While superseded by DOCX, many archived and legacy documents still use this format and require conversion for modern editing.
About DOC filesEPUB eBook
eBooksEPUB is the open standard for reflowable digital books. It adapts text to any screen size and is supported by most e-readers except Kindle. EPUB 3 adds support for multimedia and interactivity.
About EPUB filesStrengths Comparison
DOC Strengths
- Universal compatibility — every Word version since 1997 reads it natively.
- Rich feature set: styles, tables, comments, track changes, embedded OLE objects.
- Binary format means fast loading even on slow machines.
- Well-understood after decades of reverse-engineering — dozens of parsers exist.
EPUB Strengths
- Open standard — no vendor lock-in, no DRM required.
- Reflowable text — adapts to any screen size, font size, or orientation.
- Rich typography via CSS, embedded fonts, and SVG.
- Accessibility-first: native support for screen readers, adjustable text, and alt-text.
- Universal across every non-Kindle ebook reader and library app.
Limitations
DOC Limitations
- Legacy format — Microsoft stopped improving it in 2007; new features require DOCX.
- Binary structure is fragile; corruption often makes files unrecoverable.
- Historic malware magnet: embedded macros have spread viruses since the 1990s.
- Not open-standard — DOCX is the ISO-standardized successor.
- Subtle formatting drifts when opened in LibreOffice or Google Docs.
EPUB Limitations
- Kindle does not support EPUB natively (Amazon wants you to convert to AZW3).
- Fixed-layout EPUBs (for children's books, comics) are awkward to author.
- Rendering quality varies between apps — some CSS works everywhere, some does not.
- Adobe DRM (ADEPT) or Apple FairPlay are optional layers that complicate portability.
Technical Specifications
| Specification | DOC | EPUB |
|---|---|---|
| MIME type | application/msword | application/epub+zip |
| Container | OLE Compound File (Word 97-2003) | ZIP archive |
| Standard | MS-DOC [MS-OOPR] (released 2008) | — |
| Successor | .docx (2007) | — |
| Character encoding | UTF-16 LE (Word 97+) | — |
| Extension | — | .epub |
| Markup | — | XHTML 1.1 (EPUB 2); HTML5 (EPUB 3) |
| Standards | — | IDPF/W3C EPUB 2.0.1, 3.0, 3.2, 3.3 |
Typical File Sizes
DOC
- Short letter 25-50 KB
- 20-page report 150-400 KB
- Book manuscript with images 2-20 MB
EPUB
- Novel (300 pages, text only) 200-800 KB
- Illustrated reference book 5-30 MB
- Fixed-layout children's book 30-100 MB
Ready to convert?
Convert between DOC and EPUB online, free, and without installing anything. Encrypted upload, automatic deletion after 60 minutes.
Frequently Asked Questions
DOC is the legacy Microsoft Word binary format used from 1983 to 2007, storing text, images, formatting, and embedded objects in the OLE Compound File container since Word 97. It was replaced as default by DOCX in Office 2007 but remains widely used in legacy archives and older government systems.
DOC files open in every Microsoft Word version from 1997 onward, Google Docs (free), LibreOffice Writer (free), Apple Pages, and most online viewers like OneDrive and Dropbox preview. On iPhone and Android, Word apps open DOC natively.
Use KaijuConverter's DOC-to-PDF converter for a single-click conversion. Microsoft Word, Google Docs, and LibreOffice all export to PDF natively via "Save as PDF" or the print menu — the result is identical and preserves every font, layout, and image.
Always DOCX for new documents. DOCX files are 75% smaller thanks to ZIP compression, follow the ISO/IEC 29500 standard, and support every modern Word feature. DOC is essentially a legacy compatibility format — Microsoft stopped improving it in 2007.
Older DOC files could contain VBA macros that became a common malware vector in the 2000s. Modern Office blocks macros by default. If you receive a suspicious .doc, open it in Google Docs or LibreOffice first — both strip macros automatically during import.
Yes. Open the .doc in Microsoft Word and use Save As → Word Document (.docx). LibreOffice Writer offers the same export. Formatting transfers cleanly in 99% of cases; complex features like some legacy form fields may need minor manual fixes.