How to Convert OST to PST? With and Without Outlook [2025]

Did you know that over 400 million people use Microsoft Outlook for business communication? With such widespread use, managing offline Outlook data stored in OST files is critical.

But what happens when you need to access this data on a different system or want to view mailbox data on a local device? That’s where converting OST to PST becomes essential.

What is an OST File? An OST file (Offline Storage Table) is a copy of your Exchange mailbox stored on your computer. It lets you access your emails and calendar even when you’re offline or have a slow internet connection. This improves Outlook’s performance by allowing you to work without depending on a network connection.

Any changes you make in Outlook, like reading or writing emails, are saved in the OST file. When you reconnect to the internet, Outlook syncs these changes with the Exchange server.

Table Of Contents

1 What are the Key Reasons to Convert OST to PST?
2 What are Free Manual Methods to Convert OST to PST?

What are the Key Reasons to Convert OST to PST?

Converting OST files to PST format is essential in several scenarios where data accessibility and security are critical. Below are the most common reasons:

1. Creating a Reliable Backup

Backing up mail items from Exchange, Office 365, or IMAP email accounts is vital to safeguard against data loss due to accidental deletions, cyberattacks, or hardware failures. Converting OST to PST ensures your email data is preserved in an accessible format.

2. Switching to a New Organization

When moving to a new organization with a different email system, your old OST file might not be compatible. Converting OST to PST allows you to retain access to emails, contacts, and calendar entries in the new setup.

3. Recovering from a Server Crash

If your Exchange server crashes or becomes corrupted, OST files can become orphaned and inaccessible. By converting them to PST, you can recover and use your mailbox data without relying on server availability. If you are looking to retrieve and convert data from corrupted OST files, try our OST Recovery software.

4. Restoring Deleted Mail Profiles

If your mail profile is deleted from the server, you lose access to the associated OST file. Conversion to PST enables you to restore and access the mail items stored in the orphaned OST.

Each of these scenarios highlights the importance of converting OST files to PST for uninterrupted access to critical email data.

What are Free Manual Methods to Convert OST to PST?

You can convert OST files to PST for free using two common manual methods. Here’s a straightforward guide to help you:

Method 1: Use Outlook’s Import/Export Wizard

Outlook has a built-in feature that lets you export mail items from an OST file to PST format. This method works only if your Outlook profile is active and the OST file is accessible.

Steps to Convert OST to PST Using the Import/Export Wizard:

Open Outlook, go to File. Then, and then click Open & Export.
Select Import/Export to launch the Import and Export Wizard.
Click on Export to a file click Next.
Then select the Outlook Data File (*.pst) and then tap Next.
Now, choose your email profile to select all the mail folders. Click Next.
Tap Browse to select a desired location to save the resultant PST file.
At last, click Finish.

Note: Password prompt will appear. Either enter a password or leave it empty and click OK. The tool will export all your mail items from OST to PST file format.

This method is quick and user-friendly, provided you have access to the OST file through Outlook.

Method 2: Using Outlook’s Archiving Option

Outlook provides a free way to convert OST files to PST by archiving mail items. This method works for emails stored in Exchange, Office 365, or IMAP accounts. It’s a simple process to save old mail items into a PST file for long-term storage.

Steps to Archive Mail Items to PST:

Open Outlook, click File and then select Options.
Go to the Advanced tab.
Click on AutoArchive Settings.
In the AutoArchive window, set the no. of days for Run AutoArchive every “–” day.
Click OK.

This enables Auto Archiving, which saves all mail items older than the specified number of days in PST format. To save all mail items from OST to PST immediately, you can perform manual archiving with these steps:

In MS Outlook, click File and then click Info.
Next, select Cleanup Tools and then click Archive.
Select the Archive this folder and all subfolders option, then choose the email profile to include all mail folders.
Set a date.
Click Browse to select the location where you want to save the converted PST file.
Click OK.

This method is useful for organizing and backing up older emails while keeping your mailbox size manageable. However, it works only for active Outlook profiles.

What are the Pros and Cons of Manual OST to PST Conversion?

Free methods for converting OST to PST are convenient but come with certain limitations. Here’s a quick breakdown:

Pros

Cost-Free: You don’t need to spend money or purchase additional software to convert OST files to PST.
Ease of Use: These methods are straightforward and don’t typically require advanced technical knowledge.

Cons

Limited Reliability: Free methods are less dependable compared to dedicated OST to PST converter tools.
Basic Features: They lack advanced features like filters for selective conversion.
Inaccessibility Issues: These methods fail if the OST file is corrupted, inaccessible, or if Outlook encounters errors.
Large File Limitations: Manual methods struggle to handle large OST files, often leading to partial or failed conversions.
Altered Folder Structure: The original folder organization may change during the conversion.
Data Integrity Problems: Mail items might be missing or incomplete after the conversion.
No Support: If an issue arises, you’re left to rely on online forums for help, which may not always provide timely or accurate solutions.

How to Convert OST File to PST? (Using Tool)

TrijaTech’s OST to PST Converter tool converts OST files into PST, MSG, EML, EMLX, PDF, HTML, MBOX, TGZ, ICS, and vCard formats. Here’s the step-by-step information on how to convert OST to PST.

Step 1: Download OST to PST Converter. Run the tool.

Step 2: Click on Add Outlook Files option and add the OST file you want to convert.

Step 3: Click the Export button and select the file format from the given options.

Step 4: Click Convert Now to continue.

Conclusion

Converting OST to PST is essential for ensuring seamless access to your mailbox data in various scenarios, such as server crashes, profile deletions, or migration. While free methods like the Outlook Import/Export Wizard and Archiving offer a cost-effective solution, they come with limitations, such as handling large files or inaccessible OSTs.

For reliable and efficient conversion, using a professional tool like TrijaTech’s OST to PST Converter is often the better choice. These tools offer advanced features, maintain data integrity, and simplify the process. Choose the method that best suits your needs, keeping in mind the importance of securing your valuable email data.

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Deckon Rock

Deckon Rock works as a Senior Technology Writer for TrijaTech Software. He is a tech enthusiast with more than 4 years of expertise in the fields of artificial intelligence, Internet of Things, and Email Migration and Management. He enjoys doing research and offering DIY solutions for Outlook technological problems. He enjoys reading poetry and books in his spare time.