Should I convert PDF to DOC or DOCX?

Always choose DOCX. It's the modern standard. Only use DOC if specifically requested for very old software (Word 2003 or earlier).

Is DOCX compatible with old Word versions?

Yes, but may lose some formatting. Word 2007+ opens DOCX natively. Pre-2007 versions need a compatibility pack.

What is the difference in file size?

DOCX is 40-50% smaller than DOC because it uses compression. For a 100 KB document, DOCX might be 60 KB, DOC might be 100 KB.

Will DOCX work with Google Docs?

Yes. Google Docs opens DOCX files and converts them for editing. No problem there.

Is DOC format becoming obsolete?

Essentially yes. It's been replaced by DOCX since 2007 (17 years ago). Avoid DOC unless legacy support is required.

Can I convert DOCX to DOC if needed?

Yes, in Word: File → Save As → Select .doc format. But this is rarely necessary in 2024.

PDF to DOC vs DOCX: Which Format to Choose

Quick answer

Use DOCX for almost all cases. DOC is legacy format rarely needed today. Use DOC only if you're sure the recipient uses very old Word versions (pre-2007).

Key takeaways

Always choose DOCX — it's the modern standard since 2007, 40-50% smaller, and compatible with everything
DOC is legacy only — use it only when a recipient specifically requires Word 97-2003 format
DOCX has better formatting support including advanced tables, themes, and SmartArt
Google Docs, LibreOffice, and all modern editors read DOCX natively
If you receive a DOC file, convert it to DOCX in Word (File > Save As) for better handling

Understanding the formats

DOCX (Modern Word Format)

What it is:

Default format in Microsoft Word 2007 and newer
Open XML-based format
Industry standard since 2007

Compatibility:

All modern Word versions (2007+)
Google Docs (with conversion)
LibreOffice, OpenOffice
Web-based editors

File size:

Smaller than DOC (compressed XML)
Typical 20-50% smaller than DOC

Capabilities:

All modern formatting features
Track changes, comments, versions
Macros (DOCM variant for macro-enabled)
Advanced styles and themes

DOC (Legacy Word Format)

What it is:

Word binary format from Microsoft Office 97-2003
Used from 1997 to 2007 (10 years)
Replaced by DOCX in 2007

Compatibility:

Old Word versions (97, 2000, 2003)
Some older software still supports it
Newer versions (2007+) can still open, but may lose some formatting

File size:

Larger than DOCX
Not compressed

Limitations:

Cannot use modern formatting features
No track changes in new Word versions
No native support for many modern styles

Comparison table

| Feature | DOCX | DOC | |---------|------|-----| | Current default | Yes | No (legacy) | | Modern Word versions | Yes, native | Yes, but limited | | Google Docs support | Yes | Limited | | File size | Smaller | Larger | | Formatting support | Full | Limited | | Track changes | Full | Limited | | Macros | DOCM format | Supported but risky | | Age of format | 2007 to now | 1997-2007 |

When to use DOCX

Use DOCX for:

Current work (99% of cases)
Sharing with others
Long-term storage
Any use with modern Word versions
Compatibility with other software

This is the default choice.

When to use DOC

Very limited scenarios:

Recipient specifically requires it
- Example: "Please send as .doc"
- This is extremely rare (almost never happens)
Using very old Word version
- Word 97, 2000, or 2003
- Rare in 2024 (these versions are 20+ years old)
Legacy system requirement
- Old enterprise systems might not support DOCX
- Extremely rare
Deliberate backward compatibility
- Intentionally supporting very old software
- Not usually necessary

If none of these apply, DOCX is the correct choice.

Technical differences

File structure

DOCX: XML-based, compressed

Is actually a ZIP file containing XML, styles, images
More efficient, smaller size
Can be inspected with unzip tools

DOC: Binary format

Single monolithic file
Less efficient storage
Cannot be easily inspected

Formatting preservation

DOCX: Better formatting support

Colors, fonts, all styles convert cleanly
Advanced formatting (themes, effects) preserved
Margins, spacing, indentation all work

DOC: Limited formatting

Basic formatting works
Advanced formatting may be lost
Some styles don't exist in old Word

Compatibility issues

DOCX to old Word: May have issues

Open it, but some formatting lost
Advanced features not displayed
Usually still readable

DOC to modern Word: Also has issues

Opens fine, but no modern formatting
Missing modern features (themes, styles, effects)
Limiting for modern use

Impact of choosing wrong format

If you send DOCX to someone with very old Word

They can usually open it (Word 2007+ can open DOCX)
Some formatting may be lost if using very new features
Text content is always preserved
Rarely a real problem (happens almost never)

If you send DOC to someone with modern Word

Opens fine
Limited to old formatting
They cannot use modern Word features
Unnecessary limitation for modern work

Impact is usually minimal either way, but DOCX is never wrong. DOC may be limiting.

Conversion scenario

When converting PDF to Word using PDFHarbor PDF to Word tool:

Choose DOCX format (recommended)
Convert your PDF
Download the .docx file
Open in Word or compatible software
If recipient specifically needs DOC:
- Open in Word
- Save As → .doc format
- Send the DOC version

This is the only time to create a DOC file — when specifically requested.

File size comparison

Converting the same PDF to both formats:

| Document | DOCX Size | DOC Size | Difference | |----------|-----------|----------|-----------| | 5-page letter | 15 KB | 28 KB | 46% larger | | 20-page report | 120 KB | 210 KB | 43% larger | | Complex formatted doc | 300 KB | 520 KB | 42% larger |

DOCX is consistently 40-50% smaller than DOC.

Storage and archiving

If archiving converted documents:

DOCX: Better choice for long-term storage
- Standardized format
- Widely supported
- Won't become obsolete
- Smaller storage footprint
DOC: Outdated for new documents
- Legacy format
- Support declining
- Takes more storage
- May not be readable in 10+ years

Choose DOCX for any document you're storing for more than a year.

Software support for each format

DOCX support (universal):

Microsoft Word (2007+)
Google Docs
LibreOffice
OpenOffice
iWork (Pages)
Most web-based editors
Almost all modern software

DOC support (limited):

Microsoft Word (all versions)
Some older software
Some enterprise systems
Less universal support

DOCX is the safe choice for compatibility.

Macros and security

DOCX limitation: Cannot contain macros

If you need macros, use DOCM format
DOCM = DOCX with macro support

DOC advantage: Can contain macros

But macros in DOC are often disabled for security
Better to use DOCM if macros are needed

Note: PDFHarbor's conversion produces standard DOCX (no macros either way).

Summary and recommendation

| Situation | Use | |-----------|-----| | Converting PDF now (2024+) | DOCX | | Sharing with others | DOCX | | Long-term storage | DOCX | | Modern work | DOCX | | Recipient requests DOC | DOC (convert DOCX → DOC in Word) | | Very old Word version (pre-2007) | DOC | | Compatibility critical | DOCX (more compatible) |

Default answer: DOCX, always. DOC is legacy; choose only if specifically required.

For more on choosing the right conversion approach, see the complete PDF to Word guide. For a cost comparison of free vs paid tools, see free vs premium PDF to Word tools.

Related guides

Complete Guide to Converting PDFs to Word — Full conversion walkthrough
PDF to Word with Formatting Preserved — Keep formatting intact regardless of format
PDF to Word for Students — Which format for assignments and essays

PDF to DOC vs DOCX: Which Word Format Should You Choose?