No email client is as popular among working professionals as Microsoft Outlook. Ever wonder what provides strength to this popular application. Well, the answer to this query lies in its data file formats – OST and PST files. Both these file formats are responsible for the mailbox data management.
- OST files – Offline Storage Table
- PST files – Personal Storage Table
While highly encrypted OST files are more secure and can be viewed only from the linked profile, PST files are portable and can be accessed through different profiles and environments.
Outlook users need to convert OST files to PST file format for various reasons. The list of such reasons includes server unavailability, creating OST backup, and corruption in .ost file. Because of MAPIEntryID GUID, the user can’t access an .ost file from a different profile or environment. And yes, in order to access mailbox data, the user first needs to convert the .OST file into .PST format.
Notably, is no add-in in Outlook to directly perform such a conversion. However, Outlook has built-in functionalities to accomplish this task. These functionalities include the Import/Export Wizard, Archiving, and Drag & Drop. Each of these methods has some limitations, too.
Firstly, they don’t work in case of an orphaned or inaccessible OST file. Secondly, the risk of losing data is always there with these methods. In this post we will learn the best ways to convert OST files to PST format without losing data in Outlook. In addition to this, we will also shed light on an OST to PST converter tool.
Why Convert OST to PST?
Outlook users often wonder why “OST to PST conversion” is necessary. There are several reasons for this conversion. Some of the most compelling reasons are below:
- Issues Involving the Exchange Server: The conversion of .ost file to .pst format is required not only in case of exchange server crash but also when the server is undergoing maintenance.
- System Migration: In case an employee switches the job and the IT admin needs to migrate the mailbox data from one system to another, it can be done by converting an OST to PST file format.
- File Corruption: When the data file (.ost) becomes inaccessible owing to corruption, the user is unable to access Outlook. To access mailbox data, the conversion is required.
- Switching to a Different Email Client: We have discussed that OST files are compatible only with Exchange and Outlook. If the user is switching to a different client that doesn’t support the OST, the conversion becomes essential.
4 Ways to Convert OST to PST (Free and Paid)
We have discussed that that Microsoft doesn’t provide any tool for this task. Rather, this email client provides some functionalities for the same. Some of them are listed below:
Method 1: Utilizing the Import/Export Wizard
Login to the Exchange profile with which the OST file has been created. Then follow the below steps:
- Open Files
- Go to Open & Export tab
- Then click Import & Export

- A dialogue box will appear. Select Export to a file option. Click Next to proceed.

- Go for Outlook Data File (.pst). Then click Next.

- Select the targeted folder and sub-folder.

- Specify location to save the file.
- Choose Replace duplicates with items exported in order to avoid duplicate content.
- Name your PST file.
- Click the Finish tab to complete the process.

Method 2: Convert Using the Archiving Method
This manual approach prompts regular movement of OST mailbox content to a PST file. The step-by-step guide is mentioned below:
- After opening the MS Outlook app.
- Click on the File menu.
- Press the Archive tab.

- A screen will appear.
- Now select the File or Folder that needs to be archived.
- Provide location to save the archived file.

- Hit Finish
Method 3: Drag and Drop Mailbox Items
The process is straightforward. The user must first create a blank PST file. Next, they should drag and drop the selected mailbox data file from the OST to the PST file folder. It is important to note that this approach is ideal for individual email messages. This method is not recommended for complete mailbox conversion. Also, this method won’t work for orphaned or inaccessible Outlook data files (.ost).
Disadvantages of the manual methods:
- Manual methods can be time-consuming.
- Manual approaches may demand a degree of technical expertise.
- Risk of losing crucial data is always there in these methods.
- These manual methods may fail if the OST file is corrupt or inaccessible.
Method 4: Using an OST to PST Converter Tool
The professional approach to converting OST to PST files is to use a third-party converter tool. These tools are user-friendly and can maintain the folder structure during conversion. Stellar Converter for OST is a popular choice, trusted by IT administrators and MVPs. This software is based on advanced algorithms and supports Outlook versions 2003, 2007, 2010, 2013, 2016, 2019, 2021 and Outlook 365. It can even convert orphaned or inaccessible OST files to PST format. You can also opt for Technician Edition to import OST file directly to Office 365 and Microsoft Exchange.
Features
- Flawless compatibility with Windows 10 and Windows 11 (64 Bit versions only).
- Effortless conversion of OST to PST files, even when dealing with encrypted, inaccessible, or orphaned files.
- Handles unlimited file sizes without compromising speed or reliability, making it perfect for both small archives and extensive mailbox collections.
- Advanced filtering options letting you select and convert specific emails and messages based on your requirements.
- Recovery of deleted mailbox items.
- Preserves original folder structure.
Wrapping up
While Outlook doesn’t provide direct .ost to .pst conversion tools or add-ins, there are built-in features that can help when you need to convert an OST file to PST format.
While manual methods like Import/Export Wizard, Archiving, and Drag & Drop exist, they’re time-consuming and risk data integrity. Third-party tools like Stellar Converter for OST offer a more efficient and reliable solution, preserving the original file structure during conversion.


