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Summary: Are you an Outlook user who is confused about OST and PST files and doesn’t know how they differ? Then, you are not alone; many users want to differentiate between these two files. So, in this blog, you will get detailed information about OST vs PST.Also, we will recommend an OST to PST converter tool that you can use to access and convert corrupt or inaccessible OST files.

If you are among millions of people who use Outlook applications for email communication, you may have come across OST and PST files. These data storage files save the mailbox items such as email messages, calendars, contacts, and notes. Both these files are stored in your system and are helpful in recovering mailbox items when any corruption occurs.

Still, many Outlook users are confused about OST and PST. They don’t know exactly what they are and how OST and PST are different from each other. Now, you need not worry; this expert blog on Outlook OST vs PST will guide you to get detailed information about both data files and help you understand the differences between OST and PST.

What is an OST file?

An OST file (Offline Storage Table) is a data file used by Outlook to store a copy of mailbox data from an Exchange Server. It allows users to access their emails, calendar events, contacts, and other items even when they are not connected to the server. OST files synchronize changes with the server when reconnected and saved in a system with the.ost extension. If you are facing any issue with your local OST file location, you can simply change the location of the OST file in Outlook.

Instant Solution

Suggested software to access OST file’s data in Outlook. Try Kernel for OST to PST Converter to convert OST file to PST format.

What is a PST file?

A PST (Personal Storage Table) is an Outlook data file format used to store emails, contacts, calendar entries, and other data locally on a computer. It serves as a personal mailbox archive, allowing users to organize, backup, and manage their email data independently from the mail server. PST files can be created, imported, and exported, enabling data transfer and synchronization across different Outlook installations. It makes accessing and working with email information easier across multiple devices and even in offline mode.

Now it’s time to know what is difference between OST and PST in Outlook.

OST vs PST: major differences

If you are still confused between these two data files, you need not worry, as here we listed the major differences between OST and PST files.

OST(Offline Storage Table) PST(Personal Storage Table)
  • OST files allow users to work offline even in the absence of a connection with the exchange server. After the connection restored, it synchronizes itself with the Exchange Server mailboxes. This file keeps copies of items that are saved on the email server.
  • PST doesn’t allow the offline access because PST files are used for POP3, IMAP, and webmail accounts. These .pst files are created when users want to backup emails locally.
  • The OST files only support Microsoft Exchange Server.
  • PST files are compatible with Exchange and other email services.
  • OST files are encrypted with the MAPIEntryID GUID key and need authentication from the linked MAPI profile. Hence can’t be accessed or imported into any other Outlook profile.
  • PST file is importable and can be easily accessed through any Outlook profile. But it uses the CRC32 algorithm to secure PST files with a password.
  • OST synchronizes automatically and appears on the server without requiring any downloading.
  • PST synchronization requires downloading emails and local files.
  • OST files are harder to get corrupted and damaged, but sometimes it occur due to various reasons such as malware or virus intrusion, system crashes, synchronization errors, profile corruption, etc. It turns into inaccessible mode and becomes orphaned.
  • PST files can easily corrupt due to sudden system shutdown, PC crashes, power outages, etc. Even though it stores multi-gigabyte data, it becomes unstable or even inaccessible when it grows too large. Also, note that password-protected PST files can be easily accessed using third-party tools available on the Internet.
Difference between OST and PST files based on common criteria
Criteria OST PST
Dependency The OST files can’t be moved from the Exchange server independently. Possible to move and separately make a database Outlook file.
Server Support It only supports an Exchange server It supports Exchange Server and other mail servers, also
Security Encrypted using MAPIEntryID GUID key Not encrypted and is easy to access through a third-party tool
Error or Damage Hard to get corrupted and damaged Easily get corrupt or damaged
Import Only access using the original MAPI profile Easy to import into any Outlook account
Online/Offline It supports offline access to the mailbox It supports online access to mailbox items
Portability Server dependent and can’t be ported It is portable and can be saved anywhere on any local system
Synchronization Data automatically get synced after restoring the internet connection Not possible to sync automatically
Benefits Users keep working with domains irrespective of server availability It works great when users want to have a backup
How to access inaccessible and corrupt OST files?

To easily access the mailbox items ofcorrupted or damaged OST files, you need to convert them into PST. In such a situation, we recommend using an automated tool named Kernel for OST to PST converter, which is a reliable option to quickly convert OST to PST and save OST emails to Gmail,, and other IMAP servers efficiently.

You can use this PST converter tool to save the data from theft or corruption as it converts the PST files into various file formats such as DBX, MBOX, MSG, EML, TXT, RTF, HTML, and MHTML. It easily converts corrupt OST files to the desired formats.The tool also helps you recover your deleted emails with complete data integrity.


Whether it’s OST vs PST, MS Outlook keeps all information using both these file formats. OST has its own importance as it allows offline access to mailbox data; one can easily send new messages even when the system is offline or disconnected from the Exchange Server. OST files are highly encrypted, whereas PST files are easy to access without a password using a third-party tool. Still, one can access the OST file and convert OST to PST format or export it to live Exchange or Office 365 by using a Kernel for OST to PST Converter.

Q- Should I use PST or OST?

A- To choose any one among both these data files, you must be clear about your preferences. If you want to back up Outlook items on your system, you must use PST files. But, if you have an Exchange account and want to work offline without network connectivity, you must prefer OST files.

Q- What is OST and PST ?

A- OST and PST refer to file formats used by Microsoft Outlook to store data such as emails, contacts & calendar entries. OST stands for Offline Storage Table & is used to store data in an offline mode while PST stands for Personal Storage Table & is used to store data in a personal folder that can be accessed by multiple devices. 

Kernel for OST to PST