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How to Merge OST and PST Files? Tech and Non-Tech Methods

Published By Ashwani Tiwari
Tej Pratap Shukla
Approved By Tej Pratap Shukla
Published On January 16th, 2024
Reading Time 6 Minutes Reading

Today, we will discuss how to merge OST and PST file. This query has recently come into highlights and been asked by a lot of users.

PST or personal storage table are folders available in Microsoft Outlook. These folders are stored in the local hard drives of the people.

Whereas, OST or offline storage files are the files that are stored on the server. These files allow the users to work even without their server connection and users can read, compose, delete and even reply to emails in Offline mode.

There are some chances and times when users wish to merge OST and PST files.

Well, the changes made in the offline mode are later synced to the server mailbox after the Exchange connection is reestablished.

However, merging both the files seems to be a better option to users for their working conditions.

Now, it is not a very easy procedure to combine two files even if they can be access by the same email application.

Therefore, in this article, we have discussed all possible ways in which a user can easily merge his files.

Workarounds for How to merge OST and PST files

The only way to combine the two files is by first converting OST files to the other Outlook file format and then merging them both.

The first step has both professional and manual methods explained to help users have a clear vision on which one is a better option.

Manually it is going to be comparatively a more complex and time-taking procedure. Experts suggest using the professional solution to save this time and energy.

Moving on with the first method of the first step.

Step 1: Different Methods to Merge OST and PST files Explained

Method 1: Converting OST files to Outlook Data File Professionally

The OST to PST Converter can be used to convert your files that are in OST file format to the other Outlook accessible file format (.pst).

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All kinds of data whether they are emails, calendars, contacts, tasks, journals can be converted to Outlook supported format (PST).

Apart from converting the files to Outlook data file, the user can also convert them into MSG, MBOX, EML.

Whether the files are inaccessible, orphaned or large-sized they can be converted to another file format to learn how to merge OST and PST files.

Steps of the Software to Convert Outlook Accessible File (OST)

Step 1: Download the tool and then launch it on your computer system.


Step 2: Browse the OST file you want to convert.


Step 3: Now, view the browsed OST file mailbox data and click on the Export button.


Step 4: Finally, click on the PST file format and select the destination where you want to store the converted files. Hit the Export button to complete the procedure for conversion.


Method 2: How to Merge OST and PST Files Manually

Sign in to Outlook using the Exchange account used to create the OST files. And to transfer these mailboxes to Outlook data file format, simply follow these steps:

Step 1: Navigate to Files >> Open & Export and then Import &

Step 2: Select Next after clicking on Export to a file option.export-to-a-file

Step 3: Then, choose the Outlook Data File (.pst), and then hit Next.outlook-data-file

Step 4: Choose the folder you wish to export and then click Next.choose-folder

Step 5: Browse the location where you want to save the new files and hit Finish.browse-location

Method 3: Use the ‘Archive’ Feature to Convert Data

To merge OST and PST files, you can save the items from the first file separately in the second file (OST and PST respectively) by activating the Auto-Archive option in Outlook.

This approach allows you to keep the size of your mailbox under control. When the capacity of the mailbox grows and there are many messages that are older and do not need to be in the mailbox, you may quickly move them to the archive folder.

To activate auto archiving in Outlook, simply follow the steps below.

Step 1: To learn how to merge OST and PST files, launch Outlook, go to File and then select Options.

Step 2: Choose the Advanced options and then to Auto-Archive Settings.

Step 3: Set the number of days for which you want auto-archiving to run. Choose the location for the archived file, as well as the archiving parameters, and then click OK.

Step 4: Mailbox items from your OST file will be saved to the other file format in accordance with your archiving preferences.

Once done with conversion, let’s merge the converted files.

Step 2: How to Merge OST and PST Files After Conversion?

There are two methods to perform this stage. Professionally and manually can this operation be executed for the completion of merging procedure.

Take a look at the first method to merge your resultant files.

Method 1: Professionally Merging Converted Files

Using PST merge tool, both of your files can be merged easily. You can use this tool without the fear of any data loss or security issues.

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All your mails, calendars, contacts, tasks, journals etc that are in Outlook data file (.pst).

You can completely merge OST and PST files after converting for with the simple user interface for merging two or multiple files of different account.

It even maintains the folder hierarchy of the data while merging Outlook data files into a single one.

Step 1: Download and run the tool on your machine.

Add PST Files or Folder

Step 2: Select the option- Merge or Join according to the needs.

merge pst files

Step 3: Choose one of the Merge in new PST, existing PST or Outlook Profile options.  

Merge in Existing PST File

Step 4: Now, merge all the chosen files into one.

Merge PST Files Successfully

Method 2: Combine Outlook Data Files Within Outlook

For understanding how to merge OST and PST files after converting them within Outlook, you can follow a simple process that works with all versions of Outlook from 2007 to the present. It is a two-step procedure.

To begin, create a fresh blank Outlook data file (PST). After that, import your current files.

This is how it works:

1. Choose New Items > More Items > Outlook Data Files from the Home Save your blank data file with a name.

2. Go to File > Open & Export > Import/Export option to merge OST and PST files.


3. Then, go to the Import from another program or file Select Outlook Data File (.pst) on the following screen.


4. Navigate to the location of the file that you wish to import.

5. You may now replace duplicate files, allow duplicates to be created, or prohibit the import of duplicate files.


6. Once the import is finished, you may repeat the procedure to import as many files as you like into a new PST file.


There can be various reasons when the user wants to know how to merge OST and PST files. Therefore, the whole process of merging these files has been explained in detail for your ease.

You need to first convert all your .ost files into the other file format supported by Outlook i.e. PST and then merge them using a professional tool.


By Ashwani Tiwari

I am an Expert Technical Analyst, specialized in assisting users with complex technological challenges. Through my blogs and articles, I offer expert guidance to help tackle these technical issues effectively. My true passion lies in providing valuable insights and simplifying complicated technicalities, enhancing user understanding and confidence.