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Word DOC to Word DOCX converter

DOC to DOCX rewrites the old compound-file Word document as an OOXML package, exposing whether our office engine can read the legacy body.

  • Converted with Office engine · input deleted within 24 h
  • Free: 5 conversions a day · 5 MB each
  • Higher limits →

From real runs

What you get — and what changes

  • Document package Changed

    The output became a zipped OOXML package with word/document.xml, styles, settings, and content types.

  • Paragraph text Kept

    Rich DOC body text reappeared as editable Word paragraphs in the converted DOCX.

  • Heading styles Kept

    The richer DOC kept Heading1 and Heading2 style references after conversion back to DOCX.

  • Tables Kept

    The three-column migration table survived as a Word table in document.xml, with all observed cell text present.

  • Embedded image Kept

    Our office engine wrote the tiny PNG into word/media/image1.png and kept a drawing reference in the document body.

  • Footnotes Kept

    The generated DOCX included word/footnotes.xml containing the original reviewer footnote text.

  • Bad legacy source Lost

    The repository sample DOC converted to a 4.1 KB DOCX whose document.xml had no extracted body text.

Sample conversions

Rich DOC modernization

Input
Legacy DOC generated from a DOCX containing headings, a table, numbered steps, a footnote, and a small embedded PNG.
Output
The 9.1 KB DOCX contained Heading1 and Heading2 styles, word/media/image1.png, footnotes.xml, and table text for Rows 42 and Errors 0.

Minimal fixture DOC

Input
Repository sample.doc, a 9 KB binary Word fixture with no visible text recovered by the route.
Output
The API returned HTTP 200 and a DOCX package, but the main document XML contained no body text. This should not be presented as a successful modernization.

A real Word DOC → Word DOCX run

We converted our Word DOC sample (9 KB) with Office engine on 2026-09-11. It took 398 ms and produced a 4 KB Word DOCX file, 55% smaller than the input. The engine raised no warnings.

Input · sample.doc · 9 KB

OLE2 compound document (legacy Office binary)

Output · sample.docx · 4 KB

Word document: 1 paragraph, 0 headings, 0 tables, 0 embedded images; fonts Liberation Serif, Liberation Serif;Times New Roman, Liberation Sans;Arial

Paragraphs
1
Headings
0
Tables
0
Images
0
Archive parts
9
Fonts
Liberation Serif, Liberation Serif;Times New Roman, Liberation Sans;Arial

Options and when to change them

filter
Use only for advanced our office engine filter overrides when the default DOCX writer is not acceptable.

Do it yourself

LibreOffice

bash
soffice --headless --convert-to docx --outdir out input.doc

Open the output and compare body text because LibreOffice can return a syntactically valid DOCX from a DOC it did not really parse.

Word DOC to Word DOCX by API or MCP

The HTTP API and the MCP server run the exact engine this page uses (Office engine); the response carries the same warnings the web converter shows. Check support first with GET /api/v1/pairs?from=doc&to=docx.

curl
curl -X POST https://filetypeconverters.com/api/v1/convert \
  -H "Authorization: Bearer $FTC_API_KEY" \
  -F "file=@input.doc" -F "from=doc" -F "to=docx" \
  --output output.docx
API reference

When this is the wrong conversion

  • If all you need is a read-only archive, /convert/doc-to-pdf is easier to distribute.
  • If the original file is damaged, a DOCX wrapper will not recover missing text that our office engine cannot read.
  • If reviewers depend on Word comments or revision history, use the original DOC in Word before converting.

Word DOC to Word DOCX questions

Is DOC to DOCX just a file extension rename?

No. Our office engine opens the binary DOC and writes a new OOXML package with XML parts and relationships. Renaming .doc to .docx would leave an unreadable file.

Will embedded pictures move into the DOCX?

They can when our office engine imports them. In the richer run, the test PNG moved into word/media and stayed referenced from the document XML.

Why is my converted DOCX tiny?

A very small DOCX may mean the source body was not imported. Our blank fixture case produced a valid-looking package with no recovered document text.

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