How to Fix: Combine PST Files - Free (Outlook 2007, 2010, 2013, 2016)

Dennis Faas's picture

Infopackets Reader Pat C. writes:

" Dear Dennis,

I have been using Microsoft Outlook for a number of years as it is my go-to email client. Every so often I need to reinstall Windows for various reasons; when this happens I have to reinstall Outlook and create a new Outlook .PST file, which stores my Outlook data including emails and calendar. The problem is that I have 8 .PST files from each time I've had to reinstall Windows over the years, as Outlook simply - will not - allow you to continue using the same .PST file from where you last left off. From what I can tell, each time the .PST file is created it has to recreate the same data structure which essentially becomes redundant from the last .PST file. This inevitably eats up a ton of disk space. I would therefore like to merge all my .PST files into 1 file, yet I can't seem to find a way to do this without spending money on a tool to do it for me. Can you help? "

My response:

I have run into this exact same issue with a number of my clients who use Outlook and need to reinstall Windows due to severe corruption. The same thing happens if MS Office needs to be reinstalled (which includes Outlook) - the .PST file needs to be recreated. Why Microsoft won't let you continue using the same Outlook .PST file is beyond me!

Another annoying problem is that when you load an old .PST file, it creates an 'archived' inbox for that .PST file - so all your emails from previous .PST file generations are literally scattered all over the place, rather than being in a single Inbox / Outbox folder. Thankfully there is a relatively easy way to merge all the .PST files together - and without having to fork money over for a program to do it for you.

Combining PST files is free in the manner I'll describe below - best of all it works with all versions of Microsoft Outlook, including Outlook 2003, Outlook 2007, Outlook 2010, Outlook 2013, Outlook 2016 and most likely later editions!

How to Fix: Combine PST Files - Free (Outlook 2003, 2007, 2010, 2013, 2016)

To combine all your .PST files into one, you will need to:

a) create a new .PST file (by creating a new Outlook profile)

b) merge all your old .PST files into the new account

First, Create a New Outlook Profile

Creating a new Outlook profile uses the same email address and password as your existing account, so you will need to have this information handy.

To do so:

  1. Click Start, then click Control Panel, then look for the "mail" icon. Double click it, then click the "Show Profiles" button.
  2. On the next window, click the "Add" button to create a new profile, then type in the new profile name.
  3. On the next window, it will ask for your name, email address and password. Enter in this information and click "Next".
  4. Outlook will attempt to connect to the mail server using your user name and password and if successful you will have 3 green check marks. Click the "Finish" button to finish the Outlook profile wizard.
  5. IMPORTANT: Go back to the "mail" icon in Control panel and double click it to launch. Under the heading "Always use this profile", choose your new profile from the pull down menu, then click "Apply" and "OK". Your old Outlook profile will remain in tact if you need to use it, but for now we will use your new Outlook profile you just created so we can merge the .PST files together.

Second, Combine all Outlook .PST Files into One

Now that you have created a new profile, it is time to merge the .PST files together.

To do so:

  1. Click Start, then type in "Outlook" (no quotes); wait for Outlook to appear in the list and click it to launch MS Outlook.
  2. Next, click "File" -> "Open" -> "Import"; the "Import and Export" wizard will appear. Choose "Import from another program or file" and click "Next".
  3. On the proceeding window, click "Outlook data .PST file", and click "Next".
  4. On the proceeding window, click the "Browse" button to locate your existing .PST files and select one of the files. On the same window, make sure you select "Do not import duplicates" and click "Next". At this point I suggest you write down the name of the file you are importing for reference so you don't accidentally import it again. Note that importing the same file won't cause any damage but it will take some time to process.
  5. On the next screen, it will ask you to "Select the folder to import from". Make sure you select "Include subfolders", and where select "Import items into the same folder in:" and choose your email address, then click "Finish".
  6. Repeat the same steps for all your .PST files until there aren't any remaining.

Archive your old .PST files (and new .PST file)

When you are finished, all your old .PST files will be housed into a single .PST file.

At this point I suggest you:

  1. Go through your emails and calendar to make sure all the data appears to be there. If you are happy with what you see, close Outlook backup your newly created .PST file onto external storage (such as an external hard drive).
  2. Do not delete your old .PST files in case of disaster (such as your newly PST file not working properly) and you need to re-import the old data. In this case I suggest you backup the old .PST files onto external media for safe keeping.

I hope that helps.

Additional 1-on-1 Support: From Dennis

If all of this is over your head, or if you need help combining multiple .PST files into a single .PST file, I can help. Simply contact me, briefly describing the issue and I will get back to you as soon as possible.

Got a Computer Question or Problem? Ask Dennis!

I need more computer questions. If you have a computer question -- or even a computer problem that needs fixing -- please email me with your question so that I can write more articles like this one. I can't promise I'll respond to all the messages I receive (depending on the volume), but I'll do my best.

About the author: Dennis Faas is the owner and operator of With over 30 years of computing experience, Dennis' areas of expertise are a broad range and include PC hardware, Microsoft Windows, Linux, network administration, and virtualization. Dennis holds a Bachelors degree in Computer Science (1999) and has authored 6 books on the topics of MS Windows and PC Security. If you like the advice you received on this page, please up-vote / Like this page and share it with friends. For technical support inquiries, Dennis can be reached via Live chat online this site using the Zopim Chat service (currently located at the bottom left of the screen); optionally, you can contact Dennis through the website contact form.

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crackberrymeister_3399's picture

Dennis, I don't understand why a new .PST file on every reinstall. I have a home laptop and installed Office 2010, unistalled and installed Office 2013, uninstalled and installed Office 2016and removed that version and went back to Office 2010 to match my work laptop all with the same .PST file on every installation. After installing Office and then opening Outlook for the first time, it asks you to set up an email account. In the process of doing so I was given the option to use a new .PST file or an existing file. Each time I choose to use an existing file and the option box opened and I was able to point it to the existing .PST file and it opened with all my subfolders in place and my emails up to date. You can change the destination .pst file from the Mail option in Control Panel as well after selecting the Datafiles option and point Outlook to the existing file as well.

Dennis Faas's picture

I am not sure why this happens but just about every MS Outlook I've ever worked on (when users are having issues with it), I had to start a new .PST file - in fact that is the Microsoft "go to" fix if I recall. I also wrote an article about this phenomenon where Outlook outright *REFUSES* to do anything but give errors when sending or receiving emails, etc UNTIL a new .PST is created.

crackberrymeister_3399's picture

Wow that's crazy. I: have successfully used an existing .pst file to upgrade all three workstations in my office as well as my two personal laptops. Now I will state all of these systems are stand alone systems and none use an Exchange Server for email. Two have a combination of POP and IMAP accounts and the others are solely POP accounts. Not sure that would have any impact, but as stated, I have been successful on all five systems I oversee. Sorry to hear you and others have had to fight what should be a simple upgrade.

Sparkydog's picture

Did the OP try running a MS Office repair, first?