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Two Free Methods to Convert OST to PST File

Aftab Alam
Aftab Alam LinkedIn Profile | Updated On - June 07, 2023 |

Read time 12 minutes

Microsoft had designed Cached Exchange mode for Exchange Server accounts in Outlook to counter the downtime problem in mailboxes. In the absence of active connection between the Outlook and Exchange Server, the cached Exchange mode makes the mailbox available for usage.

In the offline (Cached Exchange) mode of Microsoft Outlook, all the Exchange mailbox data is present in a local file called the OST file, which stands for Offline Outlook Data file. Your local computer’s copy of your Exchange mailbox remains in OST files. Outlook stores data in OST files while you operate in offline mode. These data, however, occasionally risk becoming damaged or useless. To continue using them in this situation, you must convert them into PST files.

Due of this, Microsoft Outlook users frequently go through the OST to PST conversion process. Even when an Outlook user has to open an OST file on a different computer or format it for use in a different email program, the necessity for this conversion arises. Thankfully, there are two simple and cost-free options accessible. The steps for employing each technique will be outlined in this blog article.

Instant Solution

Recommended tool to access OST data in Outlook. Try Kernel for OST to PST Converter to convert OST file to PST format.

Some Beneficial Scenarios to Convert OST to PST Files are Here

As OST files are the data files of Exchange accounts connected in Outlook, they are helpful in multiple situations like the following:

  • A few user mailboxes get deleted from the Exchange server
  • Want to back up a few Exchange mailboxes (before the deletion of mailboxes)
  • An Exchange user wants to rebuild his corrupt OST file, but the user has some unsaved data in the OST file
  • The Exchange accounts are inaccessible due to corruption, but users want their emails urgently.
  • To re-establish email communication during Exchange downtime or unavailability
  • If you’re switching from one email client to another and your new email client doesn’t support OST files, you’ll need to convert the OST to PST in order to access your old emails.
  • If your email account has been corrupted and you can no longer access it. In this case, converting the OST to PST will allow you to access your old emails and potentially recover any lost data.

There are multiple methods to convert any OST file into PST, provided you can log in to Outlook with the same Exchange profile. Some native methods to convert OST to PST are presented here:

Method 1: Export Mailbox as a PST File

Login to Outlook with the Exchange account that was used to create the OST files. And to export the OST mailboxes to PST, follow the simple procedure as given here:

  1. Go to Files >Open & Export and click Import & Export.Import & Export
  2. Select Export to a file; then click Next.Select Export to a file
  3. Select the second option—Outlook Data File (.pst)—and click Next.Select PST file
  4. Select the folder(s) which you want to export and click Next.Select the folder to exportNote: You have the option to include subfolders as well.
  5. Browse the location where you want to save the new PST files and choose an option regarding the duplicate items.Note: There is an optional choice to provide a password to the PST file, but you can easily move ahead without choosing it.

Method 2: Use Archiving to Save OST Emails to PST

By enabling the Auto Archive method in Outlook, you will be able to save the items of the OST file in a separate PST file. This method helps you to keep the size of your mailbox manageable. When there are many older messages and you do not require them in the mailbox, you can put them in the archive folder easily. This will reduce the size of the mailbox. Follow the simple steps to enable auto archiving in Outlook.

  1. Launch the Outlook application, go to File and click Options.
  2. Go to Advanced and click Auto Archive Settings.Auto Archive Settings
  3. Now select the number of days in which you want to run auto archiving. Select the folder to save the archived file; also, provide the archiving options and finally click OK.Select the folder to save the archived fileWith this, mailbox items from your OST file will be saved to the PST file as per your archiving settings.

Method 3: Use Drag and Drop Method to Move Limited Data.

If you want to move only a selected data from your Outlook account, then you can create another data file in Outlook and drag-&-drop data from other accounts. If the size of your OST file has reached to its maximum size limit, then you can transfer data to another file and lower the data file size.

  1. First, create a new data file in Outlook. Click New Email and expand More Items. Choose Outlook Data File.create a new data file
  2. Choose Outlook data file (.pst) and click OK.Choose Outlook data file
  3. Save the PST file in an accessible folder and a new data file is created. Then, you can select some data from older account and try to drop in the new account. It will ask that if you want to move the folder inside the new account. Click Yes.Save the PST fileThe data will be moved quickly, and you can access new content there.

Method 4: Convert OST to PST Without Exchange Profile or Server Connectivity

Kernel for OST to PST Converter is a professional tool that can freely convert 25 items from each OST folder to PST. Its advantage is that it can convert offline OST files to PST without an Exchange profile or Exchange Server connectivity. It has a highly user-friendly interface that lets the user select OST file(s), recover items including the deleted ones, and convert them to PST format. Also, it can convert multiple OST files to PST at a time. Let’s see the working of the tool:

  1. Open the OST conversion tool. It will open a wizard to select single or multiple OST files. Select the OST file from its location.Select the OST file
  2. When the tool displays the OST file content, you can choose a folder and view its content in the preview pane. To convert the OST file into PST, click the Save option on the toolbar.Save option on the toolbar
  3. To save in PST, click PST file (MS Outlook) as the Output type.save in PST
  4. Select and apply the required filters – From, To, Subject, Folder Name, Item Type, and Date rangeSelect the filters
  5. You have the option to split the PST file after a certain size. Provide the required details.Select option to split the PST
  6. Browse the destination and provide the required details. Lastly, click Finish.Browse the destination
  7. When the conversion is complete, the tool shows a message showing the PST file name and its location.conversion is complete

You can manually convert OST to PST files only when you are using Outlook with the original Exchange account. But the software converts even inaccessible OST files into PST format without the original Exchange profile and Exchange Server connectivity. It can convert OST files created by webmail (IMAP) accounts too. Also, it provides many advanced filtering and saving options.


So, these are the two methods by which you can convert your OST file to PST. The first method is more user-friendly and does not require any additional software, but it is a little time-consuming. The second method is a bit complex, but it is faster than the first one. You can choose the method that suits you better depending on your needs and preferences, but you must try our recommended OST to PST conversion Tool to get the simplest resolution.

The tool has a simple user interface that makes it easy for even non-technical users to convert their files. The free trial version of the software allows users to evaluate its features and performance before making a purchase.

Q – How does Kernel for OST to PST software work?

A – The functional process of software is the same for repairing either a single or multiple OST files, and it gives a clean preview also. But the saving process is different as per the chosen destination by the user-

  1. In the Source File Section wizard, click the Browse option to select the OST files.
  2. Choose the OST file from its default location or other folder location.
  3. The software starts scanning the OST file for corruption.
  4. After scanning, the mailbox items will be listed in their actual order, and you can check their preview too.
  5. Choose the destination and apply the filters using the destination file.
  6. Choose the saving folder for the destination file.

Q – Does this OST Converter tool support the conversion of very large OST files to PST?

A – Yes, it does. It can easily convert OST files of any size to a PST file without file size limitations. While saving, the tool allows you to specify a size after which a PST file will be split, making it easier to manage.

Q – When I convert OST File to PST, will my OST data be changed in any way?

A – The software scans your file and performs a simple recovery of the whole data without affecting the integrity of the file. This tool will keep all the mailbox properties and hierarchy intact after PST conversion.

Q – Can I convert an OST file to a MBOX file?

A – Yes, you can convert OST to MBOX file, by using OST Converter software. It also gives the option to save the converted OST file in DBX, MSG, EML, TXT, RTF, HTML, XHTML, & PDF.

Q – Can we repair OST file with this OST to PST tool?

A – Yes, you can easily repair corrupted or inaccessible OST file, by using this OST converter tool. The tool helps you to repair badly damaged OST files immediately prior to conversion.

Q – Can I export/Import OST file in Office 365?

A – Yes, you can directly export OST file in Office 365, by using this OST conversion software. There are no complicated steps involved in this process.

Video – Two Free Methods to Convert OST to PST File