Difference Between Outlook OST and PST File: Complete Manual

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  • Updated on June 1st, 2022

In this blog, I am going to discuss the information related to Outlook data files. MS Outlook generates two types of data files, which are OST and PST. So we will gather some data related to this as well as finally jump into the main difference between Outlook OST and PST files.

Microsoft Outlook is a popular client which saves email data in these two file formats- OST and PST file. An OST file is created when Exchange Server synchronized email with MS Outlook clients on the local system. Another PST file is a Personal Storage Table file which stores all your personal email and their attachments in your Outlook inbox.

What is OST and PST File in Outlook?

Both OST and PST file stores an exact copy of emails with attachments of the MS Outlook application. Talking about one of the famous and popular email client today, which is MS Outlook. This email management software is a powerful tool in the Microsoft office suite. The email client comes with the regular update along with new add-on features which make the package more substantial.
In order to see the complex structure of MS Outlook, it has two files that work accordingly in the same way to another. Let us learn the difference between Outlook OST and PST files. But before that, Let’s know what are OST and PST files in the below context. You can also check ways to Convert OST to PST Manually here.

What is an ost file?

OST file is the acronym for Offline storage table and it is located in the exchange server therefore with the help of OST file the user can work in an Offline mode. When the internet connection is established again then it gets connected automatically.
The OST File is used only in the Exchange server environment and with the help of OST files, users can even reply to the sender message in the offline mode as well.

What is the .pst file?

PST file is the acronym for Personal storage table and as the name suggests, it is located on the client’s hard disk and not in the exchange server. Protocols like HTTP along with IMAP use PST files for access. Apart from that, the PST file is stored in the server as well with whom the client is syncing but never on the exchange server because a copy of the PST file is already saved there as OST.  Emails that tend to be sent and received are also stored in the PST format. Not only do PST files store calendars entries, attachments, and tasks regarding to-do lists but contacts as well.

What is the difference between Outlook OST and PST files?

Although the MS Outlook software deals mainly with the management of emails. But apart from that, it has embedded features which work amazingly well with the management of calendars tasks, to-do lists, contacts, and many others.

Rather than exaggerating the topic, diving right to the moot point which expresses the difference between Outlook OST and PST are as follows:

  1. As OST is an Offline storage folder that helps the user to work even in offline mode. On the other hand, PST is the folder which is a personal storage table that works online.
  2. OST files are bounded with the Exchange server only. But PST files can be used or can not be used with the Exchange server. With this feature of PST, it can be used or synced with other mail servers as well.
  3. OST folder can also be used when the user is online irrespective of the mode OST works efficiently. PST, on the other hand, saves local data.
  4. With the high efficiency, OST files provide the ability to work online like composing mail, sending and receiving mail in offline mode. Else PST doesn’t work this way.


I hope this information must be beneficial in the respective terms along with this you are able to get a difference between Outlook OST and PST files in outlook. If you are looking for the best OST to PST Converter, then you can check here.

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