If you are sure that the .dat file is PDF and want to open it as a PDF, right-click on the .dat file and select Open with. Then, you will see the list of programs to open with.

Once you find the information, repeat Steps 1 and 2 to open the .DAT data file in that program. Advertisement. Article continues below this ad. More For You. How to Transfer a File Using USB.

If you're having trouble opening a DAT file, I'll show you a simple and free way to do it. This method works on both Mac and PC. Just open your browser and go to winmaildat.com. It's a ...

If the DAT file is a video, you can open it with its associated video app. However, if you aren't sure what app it's intended for, VLC Media Player should be able to open it as well.