How to Compress Outlook PST Files in 2025 – Easy Guide

All MS Outlook users might know that both OST and PST files are used to store Outlook items. As they store bulk data, it is usually large-sized. Due to these large-sized PST files, your operating system might process slowly or hang. Similarly, there are various other disadvantages of keeping large PST files in your system. However, it is a challenging task to compress Outlook PST files effectively. For the process, read this blog thoroughly. 

Further, we will guide you through a reliable manual and a professional Compress PST File Converter Tool method for fast and secure results. In addition, we will discuss the advantages of compressing large PST files.

Benefits of Reducing PST File Size

You can find numerous reasons to compact them. Some of the common reasons are given below: 

• When you reduce PST file size, you can free up disk space that was filled unnecessarily. 
• Large PST files can slow down your Outlook application. However, compressing them can improve Outlook’s performance.
• If the file size is large, it will be prone to risk or corruption. So, reduce the size to avoid such circumstances. 
• In terms of backup and sharing, small PST files are easier to access and transfer in less time. 
• Through this process, you can access old emails without deleting them from your system. 

Simple Procedures to Compress Outlook PST Files

After discussing the importance of shrinking large files, let’s move towards the methods. For the process, you can use any solution. However, choose the approach wisely. If not, you might lose data during the process. Do not worry! We will help you opt for the right techniques. 

#1 Manually Compact Outlook PST File 

If you want to use manual procedures, follow the below instructions. Also, we will discuss different manual solutions one by one. 

Way 1. With Outlook Compress Now 

1. To begin, run Outlook and delete unnecessary data. 
2. Then, visit the Folder List icon.
3. Later, right-tap on the Deleted Items folder > Empty Folder.
4. After that, navigate to File > Account Settings icon. 
5. Next, tap Account Settings from the given list.
6. Thereafter, opt for the Data Files tab > Settings.
7. In the end, press Compact Now.

Way 2. Archive Feature

1. Open the Microsoft Outlook > File > Info > Tools icon > Mailbox Cleanup.
2. After that, hit the Cleanup Tools >  Archive.
3. Next, locate the mailbox folder to archive. Tap OK.

Way 3. Save in Other Format

1. To start, start Outlook and opt for emails to save them in another format. 
2. Now, press File. 
3. Thereafter, choose the Save As option.
4. Later, assign the location to save them in your system. 
5. Next, pick the desired format from the Save as Type dialogue box. Hit Save. 

Thus, all the above methods are effective. However, they lack in many ways such as being incompatible with bulk PST file compression. Also, the above procedures are more at risk as there is a high chance of human error. In that case, we have an alternative solution for an efficient and secure outcome. 

#2. Automated Technique to Compress PST File without Outlook

As you can see, the above procedures have many restrictions. The Compress Outlook PST Software is an excellent utility. With this utility, the process becomes quick and smooth. Also, it is effective to compress Outlook PST files in large numbers. Despite this, it will preserve the original folder hierarchy or data integrity throughout the process. Additionally, it provides innovative features to ease the process such as excluding or compressing attachments, and more. In addition, you didn’t have to put much effort into doing this process.  

Steps to Shrink Outlook PST File

Here is the guide to help you compress PST files securely. 

1. First, install and open the Compress PST File Wizard on your OS. 
2. Then, hit the Select Files or Multiple Files option to add the PST files that you want to compress. Tap Open >> Next. 
3. Next. view the PST file content and then tick the mailbox item for further processing. Click Next.  
4. After this, you can choose different features for effective output. 
5. Later, set the location to save the new PST file in your system. 
6. In the end, tap Convert to start compressing the large PST file. 

Conclusion

After reading this blog, you might be aware of the benefits of the process. We have also discussed the procedure to compress Outlook PST files. Typically, users prefer professional methods for quick and risk-free results. In contrast, while the native approach can be effective, it carries a higher level of risk. Therefore, if you want to complete the task without any interruptions, using automated software is the best choice.

Also Read : Import Outlook PST File to Horde Mail Server.