Updated by Tina Sieber on 17 June 2017.
Here you are, stuck with a file DAT file that was supposed to be a Word document and you don’t know what to do with it.
What Is a DAT File?
You probably wonder what a DAT file is in the first place.
Simply put, DAT files contain data in text or binary format. You’ll typically find them as winmail.dat files in email attachments, created by Microsoft Exchange Servers. But many other programs can create DAT files as well. So if the name doesn’t give it away, it’s difficult to tell whether you’re dealing with text, pictures, movies, or something completely different.
How Can I Open a DAT File?
Giving advice on how to open a DAT file of an unknown source is difficult because there are so many options, depending on the original source of the file. But say you were supposed to receive a Word document and what you did receive was a document with a DAT file extension. Basically, you have two straightforward options to open that file.
Option 1: Change the File Extension
First, you could try to change the file extension. In case you don’t see file extensions in Windows, go to the folder that contains your DAT file. In File Explorer, switch to the View tab, and click Options. In the Folder Options window, switch to the View tab once more and uncheck the option Hide extensions for known file types .
Now you can go back to your file and change the file extension from .dat to .doc, then open the file using Microsoft Word.
Option 2: Open the File
Second, you could simply try to open the DAT file with Microsoft Word or Notepad or any other program you suspect created the original file. To do this, right-click the DAT file, select Open with from the menu, then choose an application from the list. You can click More apps to show other programs than the ones suggested.
If you wanted to associate DAT files with this program (not recommended), you could check Always use this app to open .dat files.
Both of the options above could leave you with a file that’s full of gibberish, usually because you opened it in the wrong program. However, you may be able to gather what kind of file it really was. For example, if you opened a DAT file that originally was a video file in Notepad, you might find a hint that it’s actually a picture. Try opening the file in the respective program and see whether that gives you a better result.
How Can I Convert My DAT File?
Once you successfully opened the DAT file, you’re at least halfway there to converting it. But once again, there are several options.
The Easy Solutions
Let’s say we’re dealing with a DAT file that originally was a DOC file. You changed the file extension and now that you opened the file in Microsoft Word, it looks fine. In fact, you already “converted” your file. Congratulations!
If you managed to open the file with Word, the easiest way to “convert” your file from DAT to DOC, is to save the document using Microsoft Word. And there you go. It wasn’t that hard, was it?
The Serious Solution: Winmaildat.com
Now let’s get a little more serious. All the strategies above didn’t work, your file doesn’t display properly. Maybe it’s time to use a file converter.
If Microsoft Outlook messed with your email attachments, chances are that the online service Winmaildat.com will help you. If the file you need to decode is called winmail.dat or ATT0001.dat , you have certainly come to the right place.
From the Home tab, click Choose File to browse for the DAT file on your computer. You can also enter a URL. Note that the file size limit is 10 MB. Click Start and wait for the results.
Winmaildat.com will tell you the origin of the file, which gives you an idea which program you can use to open it.
Your DAT File Sorted Out
There really isn’t more to DAT files than that. To successfully retrieve data from a DAT file or convert it to its original file, you need to know the source or the original file type.
Where have you come across DAT files and how did you figure out what their origin was?