Compact Outlook PST: Step-by-Step Guide to Compress Multiple PST Files at Once
By Brian Stewart 30-10-2025 222
PST File Exceeds 50GB? Here’s How to Compress It Safely
The most popular email management software in the world is Microsoft Outlook. It saves all of your correspondence as PST (Personal Storage Table) files, including with attachments, contacts, calendars, tasks, diaries, & notes. However, over time, as your mailbox accumulates a large amount of data, the PST file size increases, slowing Outlook's performance.
In this situation, compressing (compacting) the PST file is the best solution. In this blog, we'll explore the importance of compacting a PST file, how to do it manually, and how to compress multiple PST files simultaneously using an effective third-party tool.
Why is it necessary to compress a PST file?
The more data an Outlook PST file contains, the more effort Outlook has to put into loading and processing it. Large PST files can cause several problems:
Slow Outlook: Large PST files take longer to open or search.
Possibility of data corruption: The chance of data loss rises when a PST file is larger than 50 GB.
Sync errors and freezing: Large files usually result in Outlook lagging or showing errors like "Not Available."
Difficulties with backup and restore: Backing up and transferring large PST files takes longer.
Therefore, periodically compacting (compressing) a PST file not only saves space but also makes Outlook run smoother & faster.
Two main methods for compressing a PST file:
Manual method (using options within Outlook)
Automated method (using a third-party tool)
Let's now examine both approaches in more detail.
Manual Method, How to compact a PST file within Outlook?
Microsoft Outlook has a built-in feature that allows you to reduce the size of a PST file. However, this method is time-consuming & only one PST file can be compacted at a time.
Procedure in Steps
Step 1: Open Outlook
Start the Outlook email.
Step 2: Go to Data File Management
In Outlook 2016/2019/2021/Office 365:
Go → File → Account Settings → Account Settings → Data Files Tab
Step 3: Select the PST File
Select the PST file you want to compact, then click the Settings button.
Step 4: Select Compact Now
In the new dialog box, scroll down and click the Compact Now button.
Step 5: Wait for the process to complete
At this point, Outlook will eliminate superfluous space from the PST. A few minutes are needed for this process.
Limitations of the manual method:
Can only compress one PST file at a time.
Each file must be chosen separately, & the procedure is difficult.
Corrupt PST files cannot be compacted.
Requires technical knowledge.
If you have many PST files, this method will take a lot of time. In such a case, the most suitable solution is a third-party PST compact tool.
Automated Method: Compress Multiple PST Files with PST Compact Tool
If you want to compress multiple Outlook PST files at once, manual methods aren't practical. Softaken Compress PST Tool is a smart and reliable solution.
This tool allows you to compact large and multiple PST files safely and without data loss.
Key Features of PST Compact Tool:
Bulk Compression Support:
Compress multiple PST files at once.
100% Data Safety:
Emails, attachments, contacts, and other data are unaffected.
Selective Folder Compression:
You can compress only the Inbox, Sent Items, or other folders if you prefer.
Remove Attachments Option:
To reduce PST size, you can save and remove attachments separately.
An interface that is easy to use:
Easy to use without any technical knowledge.
Full Guidance: Compress PST Files with PST Compact Tool
Step 1: Install the Software in step one.
On your Windows computer, download and install Compress PST Tool.
Step 2, Add PST Files
Add all the PST files you wish to compress by selecting the Add PST File(s) or Add Folder option on the main screen.
Step 3: Select the Compression Option
You'll get various options:
Compress Entire PST File
Remove Attachments and Save Separately
Compress Attachments Only
Choose the option that best suits your needs.
Step 4: Set the Destination Folder
Select the location where you want to save the compacted PST file.
Step 5: Start the process
Click the “Start Compacting” button.
The software will now automatically compress all PST files.
Step 6: View the report
Once the process is complete, you will see a log report showing the status of each PST file.
Bonus Tip: Some useful tips for keeping your PST file small
- Empty the Deleted Items and Junk Mail folders periodically.
Download and save attachments separately and remove them from your email.
Use the Archive feature to save old emails in a separate PST file.
Compress regularly with a tool like the PST Compact Tool.
Conclusion
Outlook PST file size growth is a common problem, but if addressed promptly, it can be easily managed.
The manual method is good for small and limited data, but the PST Compress Tool is the most effective, safe, and fast solution for large or multiple PST files.
With this software, you can compact all your PST files in just a few minutes and significantly improve Outlook's performance.
In summary:
Benefits of compacting PST:
Increased Outlook speed
Protection against data corruption
Saving space
Easier backup and management
