You're converting a PDF to Word and the converter asks: DOC or DOCX? You pick one at random and hope for the best.
Here's the actual difference and which to pick.
The short version
DOC is the legacy Word format used from Word 97 to Word 2003. Binary, proprietary, opaque.
DOCX is the format introduced with Word 2007 and used ever since. It's a zip archive containing XML — open, modern, supports more features (better images, citations, comments, tracked changes formatting).
Unless you're sending to someone stuck on Office 2003, pick DOCX.
When DOC still makes sense
Some legacy systems, government workflows, and old document management platforms only accept .doc. Specialist applications (older transcription software, certain legal billing tools) sometimes refuse .docx. If your recipient explicitly asks for .doc, give them .doc.
Everywhere else — schools, businesses, the modern Office suite, Google Docs, Pages — DOCX wins.
How Flint handles it
Flint's PDF to Word converter outputs DOCX by default. If you need DOC specifically, open the resulting DOCX in Word and use File > Save As > Word 97-2003 Document. It's a one-click downgrade.
Not every formatting feature survives the trip down — modern citations, embedded fonts and complex SmartArt may degrade. Worth checking before sending.
File size and compatibility
DOCX is typically smaller than the equivalent DOC because the XML is zipped. It also opens more reliably on phones, tablets, web Word, Google Docs and Pages. There's no real downside to DOCX in 2025 — only the question of whether your recipient's tooling supports it. If they're on anything from the last 15 years, it does.
FAQ
Will my Word open both?
Any version of Word from 2007 onwards opens DOCX. Older versions can open DOCX too with the free Compatibility Pack Microsoft released years ago.
What about Google Docs?
Google Docs handles both — uploading either format converts to a Google Doc on the fly. Download as DOCX or DOC from File > Download.
Are there security differences?
DOCX is generally safer (no macros by default in plain .docx — macro-enabled is .docm). DOC files can carry macros that older Word will run more readily.
Will the conversion be identical?
Near enough. DOCX preserves modern formatting better; DOC may lose advanced citations, comments threads, and embedded fonts.
DOCX is the default, DOC is the fallback. Convert your PDF to Word and pick whichever your workflow needs.