OST to PST Converter Tool

Powerful software to convert inaccessible OST files into Outlook PST files. The OST conversion tool converts OST file to extract all mailbox items - emails, attachments, contacts, & calendars - in PST format with 100% precision.

  • Converts encrypted OST files into PST files. Also works on IMAP OST files
  • Converts large OST files to PST - No file size limitation
  • Easily exports OST file to Office 365 & Live Exchange (Tech version)
*Free Download enables you to preview the converted file and save 20 items per folder.

Best OST to PST Converter Software

The software converts OST file to PST format and extracts OST file data as an exact replica of the mailbox data that user would have access to in normal conditions when her OST could be synchronized with Exchange. The software performs fastest conversion of OST to PST, taking approx. 7 minutes to convert & extract per GB of OST data in PST format. A software benchmark study conducted by Stellar® proves that the OST to PST converter tool performs 45% faster conversion of OST files than the second fastest competing software. Further, Stellar OST to PST conversion tool converts complete mailbox data every single time.

  • Free OST to PST conversion for first 20 emails per folder
  • Converts multiple OST files to PST format (Tech version)
  • Converts OST files of Outlook 2019, 2016, 2013, 2010, & older versions.

Stellar Converter for OST supports many use cases:

Inaccessible or Orphaned OST File

It’s common for IT administrators to come across situations like Exchange Server crash or mailbox synchronization problems which make OST file inaccessible or orphan. Likewise, a user’s desktop may fail to boot due to hardware problem or malware infection, or the storage drive containing OST file may have large number of bad sectors. The outcome of these situations is an inaccessible OST, with risk of losing mailbox data such as emails, attachments, contacts, etc. Stellar Converter for OST converts inaccessible OST file & extracts mailbox data in PST file.

Migration to New Email Service

When you migrate to a new email service or platform, it’s a challenge to gain access to the mailbox data stored in OST files of user accounts configured with older email service. This becomes a critical situation when there’s no PST backup of these OST files. In this case, you would lose the mailbox data stored in such OST files unless you convert the OST to an accessible format like PST. Our OST to PST converter software converts inaccessible OST file and extracts complete mailbox data - emails, attachments, contacts, notes, etc. - in PST format.

Migration to a New Computer

The OST file is local cache of the user’s Exchange mailbox, which can’t be directly imported in Outlook or opened on any another system. So when you change over to a new computer, the data stored in the OST will be lost unless you find a way to extract the OST data in a format like PST which can then be opened in Outlook client installed on the new machine or anywhere else. The OST PST conversion tool serves as a powerful software to convert OST file and extract the mailbox data in PST format. The software ensures that complete mailbox data is extracted

Difficulties with Using Outlook Import/Export Wizard

Outlook built-in Import/Export Wizard is an amazing utility for migrating OST data to PST format. But the tool requires users to have considerable technical proficiency and spend time to get the expected results. It also needs the same original Exchange account for this task, and you cannot convert inaccessible OST files with the help of Import/Export Wizard. Stellar Converter for OST software provides an easy and fast way to convert the OST file into PST via a rich Graphical User Interface. The OST PST conversion tool extracts OST data with 100% precision and original integrity.

Best Stellar Converter for OST Software

The benchmark study establishes Stellar® software as the tool with highest benchmark ratings on performance & reliability parameters. Software benchmark study is available here.

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More Awesome Features

Extracts Mailbox Items from Inaccessible OST to PST

There could be several situations when you may need to export the data from OST file to PST format. These could include inaccessible OST file, organization migrating to another email platform, user changing over to a new system, and more. OST PST converter quickly extracts mailbox data from inaccessible OST file and saves it in a fresh PST which can be imported in Outlook to restore mailbox access. It extracts all mailbox items including emails, attachments, contacts, calendars & deleted items. See steps to convert OST file into PST using Stellar Converter for OST.

Advance Repair

Extracts Exchange Objects from OST with High Precision

The OST PST Converter Software extracts all Exchange mailbox objects such as emails, contacts, attachments, notes, journals, calendar entries, etc. from OST files and saves them in PST format. The tool performs 100% precise OST 2 PST conversion, and maintains original integrity of mailbox items. Its advanced scan engine parses OST files of any size (no file size limitation) and extracts complete mailbox data including emails, attachments, contacts, and calendars. The software offers administrators most precise OST conversion at speed, So, it offers administrators the best of precision & speed, thereby freeing up their valuable time & efforts for more strategic projects.

Converts OST Data in Multiple File Formats

The Powerful OST to PST Converter Software also provides the option to search and save individual email messages from within OST files. In case you do not have time or do not wish to convert all OST items to PST, you can choose specific email messages to be extracted from the OST based on various parameters such as 'To', 'From', 'Subject', and 'Date' and convert them into a variety of formats including MSG, EML, RTF, HTML, and PDF formats. This feature lends this tool a high degree of flexibility, making it stand above its competition. Learn More

Advance Repair

Organizes Mailbox Messages to Improve Readability

The OST PST Converter Software extracts mailbox data in an organized manner while maintaining the original format and arrangement of items. Once OST scanning is completed and all recoverable items have been discovered, the product allows you to sort and organize your email messages by Date, From, To, Subject, Type, Attachment, Importance, etc. Additionally, it lets you improve scan result readability by allowing you to segregate emails in groups by using a convenient “Show in Groups” feature.

Converts Encrypted OST file

Users encrypt OST file to keep their important information secure from unauthorized access. Sometimes you may experience an error that it is not an Outlook Data file when trying to open encrypted OST file. In such situation, you may lose access to the data stored on your encrypted OST file. To overcome such issues, you would need to convert the encrypted OST file to PST format. OST converter tool converts encrypted OST file to PST, thus allowing to regain access of mailbox data. Learn More

Advance Repair

Free OST to PST Converter

The tool allows free OST file to PST file Conversion for 20 emails per folder. All you need to do is download the Free version of the software and scan your OST Files. After scanning, the software shows preview of converted OST file & supports free conversion for OST to PST file format. To save free 20 emails per folder, click on ‘Save converted file’ button, and the converted OST file will be saved at your specified location.

OST Conversion at Your Pace & Convenience

The software allows to save the scanned information as a DAT file which can be loaded anytime later to reinstate OST to PST conversion process. Through this feature, users can split the scan and preview instances in the process, and save the mailbox in PST without the need to repeat the scanning process. Learn More

  • Particularly used when a user is too busy to carry out the whole operation at one-go.
  • DAT file ensures that time is not wasted in repeat scanning of the same data.
Advance Repair

Batch Conversion Module

Batch Conversion procedure involves selection of multiple OST files and their subsequent conversion into PST files through a single process. This option to save the corresponding PST at the same location helps in tracing the PST files with ease. An option to save PST file at preferred (user-specified) location is also available. All OST files can be directly converted into PST files or it can be done by splitting the PST files on the basis of either “Split by Date” or “Split by Size” option. Batch conversion feature is available in Technician Edition.

Exports Mailbox Data from OST to Office 365

Migration to Office 365 is easier with this software as it can directly export the OST to PST converted files to Office 365. All you need to have is Office 365 account with valid login credentials. This software relieves you from the lengthy and time-taking mailbox migration procedure. OST to Office 365 export feature is available in Technician Edition of the software.

  • Particularly used when a user is too busy to carry out the whole operation at one-go.
  • DAT file ensures that time is not wasted in repeat scanning of the same data.
Advance Repair

Splits and Compacts Large PST Files

The Software provides two advanced options for newly created PST file: Split & Compact. To compress the converted PST file, you just need to click on “Compact & Save PST” option, and it decreases the size of PST file in the disk. The ‘Split’ feature is helpful if you have a bigger PST file and you want to split it into smaller PSTs to reduce the possibilities of PST file corruption. These features are available in Technician Edition.

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Awards & Reviews

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pc mac


Stellar OST to PST converter has worked wonders for Outlook 2003 to 2016 conversions of OST Files. This application I use and resort to.


It converts an entire OST file, or items within an OST file, into a PST without changing the original content format or structuring.

pc mac


Stellar OST to PST converter has worked wonders for Outlook 2003 to 2016 conversions of OST Files. This application I use and resort to.


It converts an entire OST file, or items within an OST file, into a PST without changing the original content format or structuring.

pc mac


Stellar OST to PST converter has worked wonders for Outlook 2003 to 2016 conversions of OST Files. This application I use and resort to.

What customers say about our Stellar Converter for OST Software?

My problem at the time was to recover an old but important Outlook file in order to retrieve the Contacts folder and older correspondence. It took three tries before I was able to successfully recover and retrieve what I wanted.

Bill Pankow

Stellar Data Recovery is impressive when it comes to any type of data recovery, the last experience made me go for Stellar once again to convert lost OST file to PST Using Stellar OST to PST Converter. I personally recommend this.

Karl Bickmore, CEO

I realized a little too late that I only had the .OST version from a prior computer and needed the .PST in order to access some files from my new machine. Happily, I quickly found the "Stellar Converter for OST".

Susan Loeper

Technical Specifications

About Product

Stellar Converter for OST



Release Date

November, 2019


Single User

Version Support

MS Outlook 2019, 2016, 2013 & lower versions.


Corporate, Technician, & Toolkit

Language Supported

English, German, French, Italian, Spanish

System Requirements

System Requirements


Pentium Class

Operating System

Windows 10, 8.1, 8, 7


2 GB minimum (4 GB recommended)

Hard Disk

250 MB of free space


Start Using Stellar Converter for OST Today With Our Free Trial.

*Free Download enables you to preview the converted file and save 20 items per folder.

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Knowledge Base & Guides

Product Related Articles

Stellar Converter for OST software Converts OST file and saves it in PST, MSG, EML, HTML, RTF and PDF formats. Learn more
Stellar Converter for OST software allows you to search a specific message and save it in different file formats — PST, MSG, EML, HTML, RTF and PDF formats. Learn more
Stellar Converter for OST converts all emails including deleted emails in PST file format. Learn more

Learn More



Use following steps for successful conversion:

  • Run Stellar Converter for OST software.
  • Select your OST file from 'Browse' option.
  • Click 'Convert' button to start the scanning process.
  • Click 'Save Converted File' button to save OST file into Different file formats.
  • Select ‘PST’ file option to convert OST file to PST format.
  • Click on ‘Browse’ button to select destination path and click ‘OK’ button.
  • Congratulations, your PST file saved at your specified location.

The software will scan the OST file and list all the mailbox folders in the left pane. Click on a folder to preview its items and save them at a destination location.


With Demo version of the software, you can save up to 20 items per folder. To save all the converted items, you would need to purchase full version of the software.


Stellar Converter for OST software allows you to search for Offline Folders (OST) files in any folder, sub-folder, or drive in your system. You can use the 'Find Outlook File' feature of the software to locate OST files in the selected drive and choose the desired file for conversion.


Conversion of OST file to PST could be required in any of the following cases:

  • Your mailbox on Exchange Server is deleted accidentally and you need to access your emails.
  • You are facing issues while synchronizing Outlook with Exchange Server.
  • You need to carry your business emails to a different workplace or organization.

The total time for converting an OST to PST depends on size of the OST file. Stellar Converter for OST takes roughly 7 minutes to convert per GB of OST file into PST, which is the top industry benchmark for conversion speed.


For importing your PST file into MS Outlook, follow these steps:

  • Start MS Outlook.
  • On the 'File' menu, click 'Open' and then select 'Outlook Data File'.
  • Choose the PST file you need to import and click 'OK'.
  • After the process is completed, MS Outlook will create a new personal folder (PST) file.

The software provides the option to save the converted OST file into MSG, EML, PDF, RTF, or HTML formats.


The Software does not perform any action on corrupt OST file. The software converts corrupt OST file into accessible PST file which you can easily import into MS Outlook to access all your OST file data.


If you face any problem during or after OST file conversion, you can contact Stellar support team


The software is available in two variants – Corporate & Technician. If you only need to convert OST file into PST format then you should go for Corporate. If you want to convert as well as compact & split large OST file then you should go for the Technician edition. The Technician edition can also export OST file to Office 365.


You can easily take backup of your Exchange data by converting the OST file to PST file format.


Yes, the software converts OST file that is not connected to Exchange Server.


Yes, the software guarantees OST to PST file conversion, however, it is strongly recommended to first try out the free Demo version of the software, which previews mailbox data stored in OST and can also convert up to 20 mailbox items per folder. Once you’ve ascertain the software effectiveness, you can activate it with a license key and then convert & save all mailbox items in PST and other supported formats.


The software allows finding the desired emails in your converted OST file and saving each email either as an EML , MSG, PDF, RTF and HTML file formats at any user-specified location in the system. You should follow the given procedure to find and save specific email messages using the software:

1. Once the scan is completed, click 'Find' button on the tool bar. The 'Search Messages' dialog box is displayed on the screen.

2. Click 'Mail' > 'Data Files'.

3. Specify the following search criteria in the dialog box:

  • To: Specify a part of the recipient's email address or the complete email address. You can separate the email addresses of different recipients using ';'
  • From: Specify the email addresses of senders. You can separate individual entries by a ';'.
  • Subject: Specify the subject property of the emails you need to find. You can provide a few characters, words, or the complete subject line of the email.
  • Date: Check the 'Select Date Field' check-box and specify the desired date. This will help to find all the emails sent or received on this specific date.

4. In the same dialog box, click 'Find Now'.

5. The software initiates the search process and displays all the found emails in the bottom pane.

6. When you right-click an email in the search results, multiple file saving formats will be displayed Choose the desired option to save the email in the respective format.


Yes, once converted, you can save the converted file in preferred format and to move that file to another system.