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What's a "docx" file, and how did I get one?


When I try to attach a document to emails I have discovered that the
recipients cannot open them. They’re telling me that there’s a ‘docx’ on the
end of the subject. I didn’t have this problem with my old computer, I now have
a gateway XP Pro.

I’m going to guess that with your new computer you also got some new
software. In fact, I’m going to further guess one of those new software
packages is Microsoft Office 2007.

If that’s the case, then what we have here is a classic cross-version
compatibility issue. Fortunately there are two ways to solve the problem.

You can solve it, or your recipients can.

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“.docx” is the new file extension that Microsoft Word 2007 uses when it
saves documents in the new default format. So you might save your document as
“letter”, but what Word 2007 writes to disk is “letter.docx” where previous
versions would write “letter.doc”. (I assume that “.docx” means .doc
“extended”, but that’s an unimportant assumption.)

As I said there are two possible solutions.

Save in the old format

In Word 2007, rather than just hitting Save, click on the
“Office Button” to drop down what we used to think of as the “File” menu, and
hover the mouse over Save As:

Microsoft Office Word 2007 Save As options

Note that I’ve called out the option so save as a Word 97-2003
. This will save the file in the format used by these earlier
versions of Word, and will do so with the normal “.doc” extension.

If you always want to save in the older compatible format you can
click on the Word Options button (always visible at the bottom
of the menu displayed with the “Office Button”), and then click on
Save at the left of the resulting dialog:

Microsoft Office Word 2007 Save Options

As you can see, you can select the Save files in this
dropdown. The default, as you might expect, is Word
Document (*.docx)
. Change that to Word 97-2003 Document
and your documents will be saved in the old compatible

“‘.docx’ is the new file extension that Microsoft Word
2007 uses when it saves documents in the new default format”

Open in the new format

I actually covered this in a previous
: there is a “compatibility pack” that users of older versions of
Word (and Excel and PowerPoint) can download and install to enable those
versions of the product to read the newer file formats directly.

In your scenario you would do nothing different. You’d keep sending out the
new “.docx” documents. Your recipients, however, would all need to download and
install the converters to be able to read what you’ve sent; or upgrade to
Office 2007.

Which is the right solution for you depends on your situation. If your
recipients expect to have lots of .docx files coming their way or just want to
be ready if and when they do, then perhaps asking them to install the converter
isn’t that big a deal. On the other hand saving in the older formats to begin
with minimizes the impact on them – at least for documents that you

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30 comments on “What's a "docx" file, and how did I get one?”

  1. Interesting tid-bit for hardcore nerds – the new Office formats (such as DOCX) are actually ZIP files. Rename a DOCX to ZIP, then open it. Ta-da! Lots of interesting XML for the text, styles, and themes – the binary files are stored in their native state. Compressing the XML can make the DOCX file much smaller than the old DOC files – often by 50%. Some folks are converting from DOC to DOCX just to save file space. This also means that information inside the DOCX can be updated without using Word. Systems that need to update content dynamically within a document can do so programmatically without using Office automation. Sweet!

  2. Hi Leo. I love your site! I just wanted to let you know that we recently encountered this problem and our solution was to open it in Pages on the Mac. My husband is a teacher and unfortunately he is stuck using a PC the school provides with next to no tech support. So, he would not be allowed to install the MS update (or any other software) and it would be difficult for him to get ALL of his students and colleagues to convert their files so that his old computer can read them. However, I told him to reference the link to this page when and if he does request the sender to convert the file. (But thats like, you know, following instructions and that is usually a lot to ask of most! ha ha ha)

    In the meantime, for us at least, it’s much easier for my husband to forward to me the email from his PC at school, I open the attachments on my Mac at home using iWork Pages, export them to Word, then re-attach them and send them back to my husband. It only takes seconds to do and is much more efficient than waiting for the response from the original sender. I just wanted to share this trick with you. Thanks again for such a wonderful reference! I share it any chance I get!

  3. Informative article, but it would be extra helpful if you included a link to where I could download the compatibility pack.

    Hash: SHA1

    The “previous article” that this article links to is about,
    and has the link to, the compatibility pack.



    Version: GnuPG v1.4.7 (MingW32)


  5. First time on your site. Quick question, I upgarded to 2007 office and for some reason my clients can not open my emails, it put my text like it is an attachment and also sends a wmv. file and another attachement. I never had a problem with office 2000. can is send my e-mail in a lower format or something??? I know about saving in WoRD and Excel to a lower version but cant figure this out. Help

  6. Hi Leo
    Could you please advise me on sending emails regarding attachement, i send files regarding applying for employment positions and i have difficulty in knowing if the recipient will receive ok and is readable, i have XP and email is outlook express 6, when sending files what format do i send them in could you please help with this problem – i was asked to send in Word Format to job application and was not sure of format…. please help

  7. I have Word 2007 installed on my laptop. Why can’t I open a docx file? What do I need to do?

    Any help you can give would be appreciated.


  8. Hi,

    I have to open MS Word 2000 document in MS Word 2003 without formatting changes.

    How can i do.

    what are the steps to be done for that.

    I need the formatting to be displayed as in MS Word 2000 documents.

    My friend told me to save the MS Word 2000 document as .docx extension will this be useful for this.

    please response.

    Thanks & Regards,

  9. I have vista and the computer won’t open any doc files. How do I get the doc file extension? Pleae help

    You probably need to install a program that understands .doc files, like Microsoft Word, the free Word Viewer, or OpenOffice.

    – Leo
  10. I needed some answers as to why I was unable to attach many of my Word files as they were the docx files. Your website was SUPER easy to understand and I got the answers to my questions right away.

  11. I have 2007 microsoft on my laptop and recently got laid off. I have been to numerous website and have tried to upload my resume and got error docx “can use this format”. I didn’t know what was wrong. Glad I found your webpage. Thanks a million.

  12. Hi Leo,

    I use Office 2010 and my work involves editing documents that I receive from many different customers. Their versions of Office range from 2000 to 2010 and I want to ensure I always send my revisions back to them in the same format they used when they sent the original files to me.
    I know how to change the default format for saving files from .dox to .doc and vice versa, but often as not I forget to check the format before I save my “_Revised” copy.
    What I’d like to do is set Office (Word in particular) so that the default is not necessarily “doc” or “docx”; I want the default to be “whatever format the original file is in when I receive it” — i.e just don’t change the format.
    Is there any way to set this? Or am I just going to have to remember to always check the format I’m saving in?

    Not that I’m aware of. You might have a peek out at to see if they have any ideas there.


  13. Just a quick comment to say I appreciate awesome guys like yourself who post answers like this to help us out. Thanks a heap! :D

  14. As outlined in above Article C3038(05.28.2007) >Changed Word Options from *.docx to *.doc successfully but how do I open files “stuck” in *.docx ? When I click a file labeled DOCX in My ocuments>Pop up “View and Track Downloads” appears with Open or Save> neither works and then Internet Expl Closes. How do I undo view and track downloads of my docs in Word ?Thanks for any help you can give me.

  15. sent post prematurely>>Details for above “Problem Solved”. Just renamed the file extension to .doc >> Now I can open all files that were previously “stuck” in DOCX.At Leo’s suggestion, I changed the “Save Files in this Format” to Word 97-2003 Documents. WE LOVE YOU LEO !! Thanks for the forum.Trish2040

  16. I am so struggling here. I am writing in Microsoft Office 2007. I write educational materials for teachers. When I send a document to the editor, I goes in the docx format. She can’t open the document. I tried saving in the Word 97 -2003 document. All my pages are messed up, text boxes flying everywhere and graphics can’t be seen. What am I doing wrong? Getting really frustrated. Thanks for the help.

  17. Leo! You’re a genius! Thanks for the tip on how to swap to Word saving as a “doc” file instead of a “docx” file. Thanks SO much!

  18. Please, I am taking University courses (an adult back to school); and I am running Windows XP on my PC. I have never used doc.x files, but this course I’m taking online requires files to be submitted as .doc or .doc s format. Could you please help me figure out how to do this? I do not use Word, so I am not really familiar with that, I only use One Note as a Biology major I don’t need these other forms usually. But do for this particular coarse I’m taking. Thank you very much.

  19. Ok, I apologize to bother you again. I printed out this page above and got my Word into the format as you describe. However, when I went to send the document to myself as a test case, my Word won’t let me send any emails. So when I hit on “send”, it opens a screen in which the email option is all light grey and doesn’t work. I have no idea why not. What now? Please advise. Thank you so much.

    You need to have an email program installed on your PC to send a Word document that way. If you don’t then instead go to your email (however you do that) compose a new email and then add the document to that email as an attachment.

  20. Hi,

    When I am trying to open a .doc file received by email the computer is using notepad automatically and I cannot read the file. The system only gives me the choice to save it as notepad nor I can use word to open.

    What can I do? how can I open directly with word?

    thanks a million

  21. @Rakel,
    You may have to save the file to your hard drive, and then right-click on it > select Open With > and choose to open with Word. Alternately, save it to disk, open your Word program and use File > Open to find the file and open it.

    You may also be able to fix this by changing the default program for opening .doc files in Windows. Here is an article on changing that in Vista.
    Where did file associations go in Vista?
    There are some links at the bottom of this article that will help if you have another operating system.

  22. I have received a docx file via email but cannot open it a message comes up saying “cannot open because it is either not a supported file type or because the file has been damaged (for example it was sent as an email attachment and wasn’t correctly decoded). Any help would be gratefully received,

  23. I have a related question to the article-what are the odds that a person won’t be able to open a docx. attachment? Is it uncommon? Should I assume they won’t be able to open it?


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