How can you reduce the size of OST files using the PST Splitter Tool?

Tips and Tricks to Split OST file

The article we’ll look at the need to reduce OST size and the solution that could break the size of huge OST in smaller units(how to split OST file).

Description: Outlook is a popular email management program created by Microsoft. It produces OST files which store information locally and allow users view emails offline. As time passes the OST file gets larger and heavy, and this is the primary reason why it will display errors. Its capacity OST file size varies between versions that comes with MS Outlook. Here is a list of capacities according to the versions that are installed of MS Outlook:

MS Outlook 2002 and before 2 GB
MS Outlook 2003 and 2007 20 GB
MS Outlook 2010 and later 50 GB

What is the reason we need to reduce the size of OST files?

In some cases, OST data files grow in size because of a huge quantity of mailbox information, and , as a result the file is damaged or corrupted. the OST file. There is also the possibility of slow synchronization, and other Outlook issues. A few common issues that allow users to Microsoft Outlook reduce OST files size are

  • MS Outlook crashes or hangs.
  • Data retrieval via the Exchange server.
  • Accessing issues in an OST file. OST file.
  • There is no way to add more data to an existing Exchange .ost file.
  • A delay in the synchronization process.

To protect your data from damage or loss, you need to reduce the OST size by following the steps provided here.

Related Post: Transfer Mac Outlook OLM Emails to MS Outlook

Methods to reduce the size of Offline data files (.ost)

There are a variety of methods to decrease the dimensions of your OST file. These methods have been proven to be safe and won’t be harmful to your files.

Make use of the MS Outlook built-in Mailbox Cleanup Utility

This process involves deleting the unwanted or old files in order in order to reduce the OST size. Follow these easy steps to tidy up your Outlook mailbox MS Outlook:

  1. Start MS Outlook and Click on the File tab.
  2. Select Tools> Cleanup Mailbox.
  3. Tap on Empty, then press Close to end the process.
  4. You can view your mailbox size before and after the cleanup procedure.

Disable Add-ins to COM

Add-ins are applications that outlook doesn’t offer. They can add memory and occupy space within Outlook’s OST file. Take these steps to delete or deactivate the Add-ins within Outlook:

  • Open Outlook and click the File menu.
  • Select Options.
  • Click on Add-ins at the bottom of the list
  • Select Add-ins to COM and hit on the Go button
  • Delete all checkboxes, then select OK

If both of these approaches don’t solve your problem of ‘How To Reduce OST File Size‘ then you can move to the next method.

The process of compressing OST files

Outlook offers an internal feature that allows you to reduce the size of your OST or PST data. The process is simple but make sure to use them properly to prevent loss of data:

  1. OPEN FILE inside MS Outlook.
  2. Go to Account settings >> Account settings then Settings for your account.
  3. Tap on Data files and choose your preferred account.
  4. Then, click the Settings button.
  5. Press the Compact Now button to Reduce the OST file size.

Archive PST and OST files

In this way, create an archive folder that will backup you OST and PST file by using the internal feature in Microsoft Outlook.

  1. Open File tab.
  2. Hit on the Tool button and select Remove old items.
  3. Tick Archive this folder and all subfolders.
  4. Now, select the folder you want to archive.
  5. Browse to the place you want and tap OK.

Professional Solution to reduce the size of OST files

This is the most effective way to cut down the OST file size in a matter of seconds. Make use of PST Splitter tool developed by Regain Software. The software lets users divide OST documents into more compact ones using various filters such as split OST files according to size the date, sender’s name as well as folders. It also comes with options like Ignore duplicate mails, password protection and numerous other.

Step-by-Step guide to split OST file using this program:

  • Download and Install Regain PST Splitter Tool .
  • Click to click the Add Files option to upload the OST files you have.
  • Click Next.
  • Now, select the desired filter, then tap Next.
  • You can input the PST file size in MB or in GB.
  • After you have used the functions, click”Split button” in order to stop the process.


In this post we have discussed the necessity to minimize in size the OST file, as well as the ways you can accomplish this task yourself. If you’re a beginner user with no any technical skills, you should go for the professional solution and free yourself from the complicated process of manual approach.

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