OST to PST Converter Tool

Powerful software Recommended by MVP's and Administrators to convert the inaccessible OST file into PST file & extract mailbox data with 100% precision. The tool converts OST to PST file efficiently and extracts all mailbox items - emails, attachments, contacts, & calendars, etc. with ease.

  • Converts encrypted OST file into PST. Also works on IMAP OST files
  • Converts large OST file to PST - No file size limitation
  • Exports mailbox data from OST to Office 365 & Live Exchange (Technician Edition)
*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 to PST and extracts items from Offline Outlook Data File (.ost) file as an exact replica of the mailbox data that user would have access to in normal conditions when 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 tool performs 45% faster conversion of OST files than the second fastest competing software. Further, Stellar OST to PST conversion tool extracts complete mailbox data every single time.

  • Allows free OST to PST conversion of first 20 emails per folder
  • Converts multiple OST files to PST format in a batch (Technician Edition)
  • Converts OST files of Outlook 2019, 2016, 2013, 2010, & older versions.

When to Use Stellar OST PST Conversion Tool?

Need to Extract Data from Inaccessible OST?

Exchange Server crash and mailbox synchronization problems can turn OST file inaccessible or orphan. Similarly, a client machine may fail to boot due to hardware problem, crash, or malware infection, or the drive containing OST file may have large number of bad sectors. These situations ultimately result in inaccessible OST with risk of losing critical mailbox data if there’s no backup. With Stellar tool, you can convert OST to PST & extract mailbox data including emails, attachments, contacts, etc.

Are You Migrating to a New Email Service?

When you migrate to a new email service, it may be a challenge to access mailbox data stored in OST files of user accounts that are configured with older email service. This might turn into critical situation in case if there’s no PST backup of the OST files, as that would result in loss of unsynchronized mailbox data inside OST. Stellar tool addresses such email migration challenges by allowing to convert OST to PST and extract mailbox data - emails, attachments, contacts, notes, etc. in a portable format. The resultant PST can be imported in a compatible email service.

Changing Over to a New Computer?

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 retrieve it in a portable format such as PST. Stellar OST PST conversion tool makes this possible by converting OST file and extracting mailbox data in PST format, which can be opened in Outlook client installed on the new machine.

Facing Difficulty with Outlook Import/Export Wizard?

Outlook Import/Export wizard is a great built-in utility for exporting mailbox data from OST to PST for Exchange connected accounts. However, it cannot extract data from inaccessible OST, i.e. Offline Outlook Data files without Exchange account. Further, Outlook Import/Export utility requires users to have 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 a hassle-free and reliable solution for converting OST file into PST. The OST PST conversion tool extracts mail items with 100% precision and original integrity.

More Awesome Features

Extract Mail Items by Converting Inaccessible OST to PST

Has Exchange crashed and you're facing mail synchronization problems, system hardware has crashed or users are changing over to new machines? These situations might result in OST file inaccessibility, creating the need to open OST file without Exchange for extracting ‘locked out’ or unsynchronized data. Trust the leader when you need a reliable tool for extracting mail items from inaccessible OST. Stellar Converter for OST helps as a professional solution to rescue mailbox data from inaccessible OST in several such situations, when Import/Export wizard is of no use and you can’t trust just any tool with your emails and other mailbox data.

Advance Repair

Extract 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, thereby freeing up their valuable time & efforts for more strategic projects.

Convert OST Data in Multiple File Formats

The Powerful OST to PST Converter software allows searching and saving individual emails from OST file. 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

Organize 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 sorting and organizing email messages by Date, From, To, Subject, Type, Attachment, Importance, etc. Additionally, it offers enhanced view of the scan results by allowing to segregate emails in groups by using “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 Free version of the software and scan the OST file. 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 the conversion process. Using this feature, users can split the scan and preview instances in the process, and save mailbox data in PST without the need to repeat the scanning process. This feature is helps users to avoid spending long durations to scan and retrieve mail items from large OST file in a single stretch. Learn More

Advance Repair

Converts Multiple OST in a Batch

The tool can perform batch conversion of multiple OST files into PSTs through a single process. This makes it convenient in situations wherein data needs to be extracted from several OST files, for example, when an organization is moving to a new email service and needs to extract mailbox from several inaccessible OSTs. Further, the option to save the resultant PST files at the same location helps in tracing them later. Batch conversion feature is available in Technician Edition of the software.

Exports Mailbox Data from OST to Office 365

The software supports mailbox migration to Office 365 as it can directly export the OST to PST converted files to Office 365. All you need is an Office 365 account with valid login credentials and the software can allow export of mailboxes to O365 by connecting through its interface. OST to Office 365 export feature is available in Technician Edition of the software.

Advance Repair

Splits and Compacts Large PST Files

Technician edition of the software can split large Outlook PST file thus reducing its chances of corruption and improving long-term manageability of emails. It can split PST by Size, Date, Email ID, and Folders, while maintaining original structure and organization of emails. Likewise, it can compact PST file to ensure optimal performance of Outlook without lag or crash. It optimizes PST file size by compressing all attachments in a new folder and emptying ‘Deleted Items’ and ‘Junk Items’ folders. Learn more.

Steps to Use Stellar Converter for OST

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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 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


Download now to start using Stellar Converter for OST

*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 or PDF format. Learn more
Stellar Converter for OST allows you to search individual email messages and save them in different file formats such as PST, MSG, EML, HTML, RTF and PDF. 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.