What Is a PST File?
A PST file is an offline storage container used by Microsoft Outlook to hold your emails, contacts, calendar events, tasks, and notes that grows as you add more data like sending emails or saving attachments.
Over time, a PST file could grow. When PST files are large, Outlook may run slowly, freeze, or display error messages like “Outlook data file has reached maximum size” and others
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Splitting a PST file can make Outlook work better. Before exploring the how to, let’s look at why it’s a good idea.
Why Split a PST File?
A large PST file can cause issues, and splitting it offers clear benefits:
- Better Performance: Smaller files allow Outlook to process data faster, reducing wait times.
- Fewer Errors: Large files are more likely to get damaged; splitting lowers that chance.
- Size Management: Older Outlook versions limit PST files to 20 gigabytes, while newer ones allow 50 gigabytes splitting keeping files within these limits.
- Easier Organization: You can separate data, like work emails from personal ones, for quicker access.
If you’ve noticed Outlook acting up or want to avoid problems, splitting your PST file is a practical fix.
Can You Split a PST File Yourself?
Yes, you can split a PST file using tools already available in Outlook or on your computer—no special purchases are required. The process works best if your file isn’t too large (under 20 gigabytes is easier) and isn’t damaged.
Note: If Outlook won’t open your PST file, it might be broken. Use the free SCANPST.EXE tool (found in your Outlook folder, like C:\Program Files\Microsoft Office\root\OfficeXX) to fix it first. Run the tool, select your PST, and click Repair.
Also Read: How to Reduce OST File Size?
DIY Methods to Split a PST File
Here are three do-it-yourself ways to split your PST file, complete with steps and tips to handle common issues.
Method 1: Move Data to New PST Files
This method lets you create new PST files and move specific emails or folders into them great for organizing by topic or person.
- Open Outlook: Start Outlook on your computer and make sure your PST file is loaded. Check this by going to File > Account Settings > Data Files.
- Create New PST File: Click on Add and name and save it in a folder you can find, such as Documents.
- Choose Data to Move: Look at your inbox, sent items, or folders. Decide what to split—like all emails from a coworker or a folder called “Receipts.” If needed, make new folders by right-clicking your mailbox and selecting New Folder.
- Move the Data: Right-click the emails or folder, choose Move > Copy to Folder, and pick your new PST file. Repeat for other groups.
- Check File Size: Go back to Data Files, select each PST, click Settings > Advanced, and see its size. Keep each under 10 gigabytes for best results.
- Remove Old File (Optional): Once everything’s moved, disconnect the original PST in Data Files by selecting it and clicking Remove. Keep it until you’re sure all data is safe.
Tip: If moving takes too long, try smaller batches (e.g., 200 emails) or close other programs to free up your computer’s memory.
Method 2: Use Outlook’s Archive Feature
Outlook’s built-in archive tool splits off older data into a new PST file perfect if you want to keep recent emails separate from old ones.
- Access Archive: Open File > Tools > Clean Up Old Items (or File > Info > Tools > Archive in newer versions).
- Set a Date: Choose a cutoff date, like “items older than January 1, 2024.” Select where to save the new PST file and click OK.
- Run the Archive: Outlook will move all emails before your date to the new file, leaving newer ones in the original PST.
- Verify Sizes: Check both files in Data Files > Settings > Advanced. If the original is still too big, archive it again with an earlier date.
- Find Your Data: The new PST appears in Outlook under “Archive” or can be opened via File > Open & Export > Open Outlook Data File.
Tip: If archiving fails, check that your PST isn’t set to “read-only.” Right-click the file in Explorer, select Properties, and uncheck “Read-only.”
Method 3: Split by Date Ranges Manually
This method splits your PST by periods using Outlook’s search and move features.
- Open Outlook: Start the program and load your PST file (File > Account Settings > Data Files).
- Create New PST Files: Go to File > New Items > More Items > Outlook Data File. Make one for each date range, name them, and save.
- Search by Date: In your inbox or folder, click the search bar, then Search Tools > Search > Advanced Find. Set a date range and click Find.
- Move Results: Select all found emails (Ctrl+A), right-click, choose Move > Copy to Folder, and pick the matching PST. Repeat for other years.
- Confirm Sizes: Check each PST in Data Files > Settings > Advanced aim for 5-10 gigabytes per file.
- Clean Up: Disconnect the original PST in Data Files > Remove after verifying the moves.
Tip: If search results are slow, narrow the date range or restart Outlook to refresh.
Precautions to Take
- Avoid Changes: Don’t add new emails while splitting to keep things consistent.
- Make a Backup: Copy your PST to a USB drive or cloud service (like Google Drive) before starting.
- Act Early: Split your file as soon as Outlook slows to avoid bigger issues.
Conclusion
Splitting a PST file is a simple way to improve Outlook’s performance and keep your data organized. This guide offers three DIY methods moving Outlook data to new files, archiving old items, and splitting by date—all using tools you already have. Follow these steps to manage your PST file easily and avoid trouble.
