DOC to DOCX Converter

AUTO-DELETE/Files are processed on our server and deleted as soon as conversion finishes.

or drop your images here

How to Convert DOC to DOCX Online

DOC to DOCX: what changes in the file

This tool takes a DOC file, converts it with LibreOffice running on our servers and returns a DOCX file.

DOC is the old binary Office 97–2003 format and DOCX the current XML format: the file gets smaller, opens in current Office and nothing is lost.

How DOC and DOCX differ

Property	DOC	DOCX
Full name	Word 97–2003 Document (binary)	Office Open XML Document
Introduced	Microsoft, 1997	Microsoft, 2007 (ISO/IEC 29500)
Data type	laid-out document	laid-out document
Strengths	opens in every version of Word, including very old ones	current Word format; smaller than DOC (ZIP of XML)
Limitations	legacy binary format; larger files and weaker compatibility with modern features	Word 2003 and older need a compatibility pack

Measured with a sample file

On September 25, 2026 we ran the tool on our production server with a sample file: a one-page document with a heading, Vietnamese text and a table (DOC), 20 KB.

Result: 20 KB → 7 KB, processed in 3.5 s. Output: a valid DOCX file (file signature checked).

Real sizes depend on document length, embedded images and fonts; the figures only show the order of change.

Before you convert

The server has DejaVu and Liberation fonts only. Times New Roman, Arial and Courier New keep their layout (Liberation matches their metrics); other fonts such as Calibri or Cambria are substituted, so line breaks and page count can change.
Up to 100 MB per file; a conversion that runs longer than 2 minutes is cancelled.
The file is sent to our server for conversion and deleted as soon as processing ends, including when it fails.

Frequently asked questions

Is any content lost converting DOC to DOCX?

No. DOCX can hold everything DOC contains, and the file is usually smaller thanks to ZIP compression.

Why did the page count or line breaks change?

The document uses a font the server does not have (only DejaVu and Liberation are installed), so a similar font is substituted. Times New Roman, Arial and Courier New are not affected.

How does the file size change from DOC to DOCX?

With our sample file: 20 KB → 7 KB. Your file may differ depending on its content.