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How to Convert OST to PST Free

5 Min. Read

Microsoft Outlook maintains mailbox contents inside an Outlook data file. Based on the email account type (IMAP/MAPI/POP), Outlook may build an OST file or Personal Storage Table (PST) file to keep a synchronized copy of mailbox contents on the local machine.

Thanks to the OST file, and Offline Outlook, users may access their mail items even when the PC is offline or when the server is momentarily unavailable. However, this information is locked behind a MAPIEntryID GUID key and cannot be accessed or imported into another Outlook profile.

This guide will show you how to convert OST to PST files so you can access them or import them into another Outlook profile.


When it comes to archiving and migrating mailbox contents across Outlook profiles, PST is the most frequently utilized file type. In both Outlook for Windows and Mac, PST files may be opened and imported into a new or existing Outlook account. Live Exchange Servers and Office365 may also import PST files (Microsoft 365).

Using the Outlook Import and Export Wizard, you may export or import the mailbox items into or from a PST format.

You can also convert your Outlook OST file into PST format to import or migrate your mail items from an Outlook OST file to another computer, an Outlook profile, a live Exchange Server, or Office 365 both online at or by installing the software on your computer at

Convert Outlook OST file into PST format
Convert Outlook OST file into PST format

Converting from OST to PST is also necessary when the OST file reaches the orphaned stage or becomes unavailable for several reasons, including the following:

1. The mailbox profile was removed from the Exchange server and deleted.
2. A sudden shutdown or breakdown of the system.
3. Large size OST file (oversizing).
4. Virus or another malicious software compromise.
5. Add-ons that are either defective or incompatible.

To recover a mailbox removed from the server inadvertently or deliberately, Exchange administrators may also be required to convert offline OST to PST files within Outlook 2010, 2013, 2016, and 2019.

This post will explain free techniques that may convert OST files to PST format.

Manual Methods to Convert OST to PST Files

Using the Outlook Import and Export Wizard, you may export the mailbox items into PST format by taking the following steps:

Step 1: Use the Outlook Import and Export Wizard

The Outlook Import Export Wizard allows users to export mail items and contacts to the PST or CSV file formats.

• In Outlook 2010, go to the File menu, pick Info, and then click the Options button.
• To launch the Outlook Import Wizard, pick Advanced from the menu, and then click Export.

• To import or export data in Outlook 2013, 2016, or 2019, go to the File menu, Open & Export, and click Import/Export. The Outlook Import Export Wizard will now be available to you.

Outlook Import/Export
Outlook Import/Export

• In the box labeled Import and Export Wizard, choose to Export to a file, then click the ‘Next‘ button.
• Select Outlook Data File (.pst) from the drop-down menu in the Export to a file box, and then click Next.
• Select the mail folders and items you want to convert to PST, and then make sure the “Include subfolders” selection is selected. Then click the Next button.

• After deciding where to save the converted PST file, choose it using the “Browse” button and then click the “Next” button.
• Click the “Finish” button. After that, you will be prompted to enter a password or click the “OK” button without entering the password.

For more information, check the official documentation about import and export Outlook email, contacts, and calendar.

Step 2: Drag and Drop Emails to New PST File

You can also move emails from an OST file to a PST file. To do this, you will need to use the options provided by Outlook to create a new PST file.

Drag and Drop Emails to New PST File
Drag and Drop Emails to New PST File

The following is a list of the steps:

• To open an Outlook data file, go to New Items > More Items > Outlook Data File
• Select a location, type in the name you want to give the PST file, and then click the “OK” button to create the PST file.
• Now, using the OST mailbox you wish to convert to PST, select all of the items in the mailbox’s mail folder then drag and drop them into the freshly formed PST file.

Step 3: Use Outlook Archive Option

The Archive Settings in outlook may also automatically store mail items in a separate PST file.

Outlook Auto Archive Settings
Outlook Auto Archive Settings

The following is a list of the steps:

• Choose File > Options > Advanced from the menu bar.
• Hit the option labeled “Auto Archive“.
• Choose the number of days you want to run the Auto Archive process.
• After clicking the “Browse” button, you can choose a place to store the produced archived PST file.
• The next step is to proceed by selecting “OK“.

Items from your mailbox will be automatically copied into the PST file from this point forward.

Offline Methods to Convert OST to PST Files

The Offline OST to PST Converter is one example of a professional solution that can help you convert OST files to PST files and overcome the abovementioned constraints.

When you cannot log in to your Outlook account or launch the Import Export wizard, you may put this tool to good use.

This tool may convert a single or numerous inaccessible or orphaned Outlook OST files to PST format. Additionally, you can export the mailbox contents from the OST file straight to an existing Outlook profile, Office 365, live Exchange, or any other file format you want.

You may download the program at no cost, and the trial edition allows you to convert and preserve a limited number of mail items in each folder. In addition, you may activate the program using a valid activation key to save all items in your inbox to PST or other formats.

When converting OST files to PST, the program can retrieve inadvertently deleted emails.

The following is a list of all the steps:

• After downloading, installing, and starting the Offline OST to PST Converter program, choose the OST file from the drop-down menu. The OST files stored in the default location are shown when you click the Default Location option. You may manually choose the location of the OST file by using the option labeled “Choose Location“. Click “Next” to continue.

Offline OST to PST Converter
Offline OST to PST Converter

• Next, select the work mode (Converter mode). The Recovery mode is used when you have a corrupted PST/OST file, and the Converter mode is used when you have a healthy OST file and you need to convert it into a new PST file.

Converter mode
Converter mode

• Following the completion of the conversion, the program presents an improved glimpse of all of the mail items included inside the OST file. Simply selecting one of the scanned OST file’s mail items with a click will allow you to see and pick all of the other scanned mail items. Click “Next” to continue.

Preview of data to be recovered
Preview of data to be recovered

• After selecting a place to store the file, choose “Browse” and click “OK“. Click “Next” to continue.

Target folder for saving recovered data
Target folder for saving recovered data

• Next, choose the ‘Save as PST’ option as shown in the figure below.

Select the type of save
Select the type of save

• This will store the converted OST file in a format that can be imported into Outlook, which is PST.

Save as PST file
Save as PST file

You will need the Offline OST to PST Converter program to export the OST straight to an existing Outlook profile, import the OST into Office 365, or work with live Exchange (free demo version available).

Even while the Outlook Import Export Wizard may export the mailbox items from your Outlook profile to the PST format, you should avoid using it if you need to convert a large number of OST files at once.

In addition, there is no ability to convert large OST files into several smaller PST files that may be managed individually. Additionally, it exports all of the mail items in a single PST, which may lead to difficulties with the file’s integrity and corruption.


In this article, we showed you how to convert OST files to PST for free using the manual approach, as well as using the offline OST to PST converter free tool.

You may convert large-sized OST files, as well as inaccessible and orphaned files, to the PST format by using a program called an OST to PST converter. You can also export the OST file straight to a live Exchange server, Office 365, or an existing Outlook profile.

> Learn more about how to recover corrupted PDF Files.

Thank you for reading my blog.

If you have any questions or feedback, please leave a comment.

-Charbel Nemnom-

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About the Author
Charbel Nemnom
Charbel Nemnom is a Senior Cloud Architect, Swiss Certified ICT Security Expert, Certified Cloud Security Professional (CCSP), Certified Information Security Manager (CISM), Microsoft Most Valuable Professional (MVP), and Microsoft Certified Trainer (MCT). He has over 20 years of broad IT experience serving on and guiding technical teams to optimize the performance of mission-critical enterprise systems with extensive practical knowledge of complex systems build, network design, business continuity, and cloud security.

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