How to convert ANSI PST to UNICODE PST format and Vice Versa Manually

PST upgrade and downgrade

Do you want to avoid file corruption due to limited 2 GB file size in PST files then you need to upgrade PST file? The earlier version of Outlook used ANSI PST format for storing all the data files. The version 2003 of Outlook came with another format called Unicode PST format. Sometimes the user needs to downgrade Outlook or Upgrade Outlook due to numerous reasons, personal or official or other. Here this blog explains you the manual process to Convert ANSI PST to UNICODE or UNICODE PST to ANSI. Let’s proceed with learning the difference of ANSI format and UNICODE format.

What is ANSI PST and Unicode PST?

upgrade ANSI PST difference to Unicode

Outlook 2002 and older version supported PST file of ANSI format, store all mailbox with 2 GB limitation of files. ANSI uses old character encoding which supports the 8-bit character set on stored data.
After the version 2003 Outlook introduced a new PST format Unicode which extends the limitation of ANSI PST from 2 GB to 20-50GB and more. The Unicode format uses a UTF-8 encoding that has the ability to encode all type of character used nowadays.

This is the reason why Outlook has upgraded ANSI PST to Unicode PST format. Many Outlook users want to know how to convert the ANSI PST to Unicode format. Unfortunately, there is no direct way convert a PST from Outlook97/2002’s ANSI to Unicode(or from Unicode to ANSI). Let’s go on and know the process.

Determine the Outlook format ANSI or UNICODE.

Most of the user face an issue in identifying the PST format they are working on ANSI and UNICODE. As we have learned that there is the great difference between ANSI and Unicode then we must have the knowledge to identify the format. Before that identify your version of Outlook. In Outlook, go to help menu and select About Microsoft Outlook.
outlook versionNow the follow the step to know the steps to know the PST format on which we are working with.

determine pst format
Steps in Outlook 2010, 2013 and 2016:

  • Open MS Outlook >> Click on File menu >> Info at the left pane.
  • Select Account Settings option >> Account Settings >> hit on Data Files.
  • Double click on the path named as a .pst extension, popup windows will appear.
  • On the pop-up window, if the Format field is named as Outlook Data File or Personal Folder File, then your PST file support UNICODE format.
  • If the Format field is named as “Personal Folders File (97-2002)” or “Outlook Data File (97-2002)”, then your PST file support ANSI format.

After we upgrade Outlook version to the newer one, for example; Outlook 2002 to 2010, PST file is not automatically upgraded.

Even though we have upgraded or downgraded the version of Outlook in our system the PST format remains same as earlier that is ANSI is not converted to Unicode and Unicode is not converted to ANSI. For this, we have to Upgrade PST or downgrade PST file(depends on user need ) by hands.

How can we Upgrade ANSI PST file to UNICODE PST format?


  1. First thing, launch Microsoft Outlook application and create a new PST file.
    (If Outlook 2010 and newer, click New Items > point to More Items and click Outlook Data File. if Outlook 2007 or 2003, click File menu > New and click on Office Outlook Personal Folders File.) and click ok.
  2. Set the location and name the new PST file as you want.
  3. Now go to the older PST file.
  4. Finally, move all the folders from ANSI PST file to the newly created Unicode PST file by drag and drop feature.

The above-described technique will help you to upgrade your MS Outlook PST files. To downgrade PST files, you need the exactly same steps. Where Downgrade in Outlook word means to convert a Unicode PST file into ANSI format. Though this is not mush required in most cases, sometimes it is essential in order to maintain the portability to lower MS Outlook versions.


The manual technique mentioned is considered an easy and effective way to convert ANSI PST to Unicode PST format, but sometimes it may become quite challenging for Outlook users. Especially when it come to converting the large PST file that may contain a lot of folders. To convert ANSI PST to Unicode PST smoothly you should try PST Upgrade and Downgrade Software. The Software makes the task non-challenging, you just have to select the files to upgrade PST and the software will process its task, the job is done that all. To know more about the software you may visit SysInfoTools Blog Convert ANSI PST to Unicode