How to Split a Large PST File by Size, Year, or Date (3 Free Methods + 1 Tool)

Using Outlook's Import/Export wizard or the Archive option, you can split a PST file into smaller parts. You can also try moving emails from the current mailbox to a new .pst file. There is also Stellar Splitter for Outlook - a specialized PST splitter tool that splits PST files by size, date range, year, email ID, or folder in a few steps. In this guide, we will discuss the benefits of splitting the PST file and explore these methods in detail.

What are the Microsoft-Defined PST File Size Limits?

According to Microsoft's published documentation, PST files that approach or exceed the predefined size limits can cause performance and other issues, such as Outlook fails to store new mail or becomes prone to corruption – in Outlook. The table below shows the PST file size limits for all versions of MS Outlook on Windows.

What are the Common Problems caused by Large PST File?

If your PST file becomes large or exceeds the stipulated limit, then you can encounter several issues, such as:

• Slow or sluggish Outlook client performance
• Outlook fails to store new emails or other mailbox items in the PST file
• PST file corruption
• Encountering errors, like “The file xxxx.pst has reached its maximum size”

To avoid such issues, it becomes important to split a PST file into smaller parts.

Why to Split a Large PST File?

Here are some benefits of splitting large PST file into smaller parts:

• Better Performance of Outlook: If the file size of a PST file is >10 GB, you may notice slow search indexing in Outlook. It also affects email message loading times. When you split a PST file – by year, email ID, or folder – the information gets segregated into separate .pst files, which reduces the file size and thus helps improve the performance of the email client.
• Less Chances of PST File Corruption: Large PST files are susceptible to corruption or damage. It is common when the file's size is close to or exceeds the predefined limit — 20 GB for Outlook 2003–2007 and 50 GB for Outlook 2010 or later. Splitting the large PST file into smaller files can help reduce the risk of corruption to a great extent.
• Easier to Share: It becomes easy to share smaller PST files with other Outlook users. For example – a 50 GB PST file cannot be sent over email or uploaded to most cloud storage services within standard size limits. Splitting it into several smaller files (5GB each) makes sharing between users or systems practical.
• Better Organization: Smaller PST files can help you organize emails and other items in a more efficient way. Users can split PST files by year - a logical way to create a single mailbox file per calendar year — 2022.pst, 2023.pst, and so on. This makes it simple to locate and open emails from a specific year without going through the entire email history.

Methods to Split Large PST File into Multiple Smaller Parts

Below, we have discussed different methods to split PST file into multiple smaller parts by size, year, and date.

Method 1: Split PST using Outlook Import Export Wizard

MS Outlook has an inbuilt feature – Import/Export wizard - that lets you export mailbox items to PST file. You can use this feature, as a workaround, to split your PST file by exporting mailbox items to multiple smaller files. Let’s see how:

When to use this method: It can be used for selective mailbox folders or items export to a new PST file. You'll need to manually choose which folders/items to export.

• Launch the installed Outlook desktop application.
• Go to File > Open & Export > Import/Export.

• The Import and Export wizard will open. Select the Export to a file option and click Next.

• A new window will open. Select the Outlook Data File (.pst) option and click Next.

• Select the items/folders you want to save in a new PST file. Click Next.

• Browse and select a location to save the new PST file.
• Click Finish. It will commence the export process.

You may use the process again in case you wish to create more .pst files.

Note: Doing this will not automatically reduce the size of your primary PST file. You'll need to delete the exported items from it after following the above process.

Method 2: Split PST using Outlook Archive Option

Another feature that you can use in Outlook to split large PST file is "Archive." Here's how it works:

When to use this method: Ideal for splitting PST files by date. It is the only built-in feature in Outlook that automatically filters items by date.

• If you’re using Outlook 2024, 2021, 2019, and 2016, go to File > Info > Tools > Clean up old items. If you’re using Outlook 2013, click File > Info > Cleanup Tools > Archive.

• The Archive window will appear. Choose the Archive this folder and all subfolders option.
• Select the mailbox folder/s that you want to archive.
• Enter the date against the Archive items older than option.
• Select the Include items with “Do not AutoArchive” checked option.
• Click on OK.

You may also refer to Microsoft's official guide to Archive items manually.

Method 3: Move Items to a New PST File

You can manually move (drag-and-drop) specific email messages, contacts, or any other mailbox item from your primary PST file into a new one – from within the Outlook client. Unlike the Import/Export method, you can use this to drag and drop the required emails or mailbox items directly inside Outlook. Hence, it is ideal for moving individual items rather than exporting an entire folder/s. Here is what to do:

• Launch Outlook on your Windows PC.
• Click on Home and then on New Items on the ribbon.
• Go to More Items > Outlook Data File.

• It will open the Create or Open Outlook Data File window.
• Select the location/folder where you want to save the new PST file on the system.
• Give the file a name and click on OK. The newly created PST file will be listed in the left pane in your Outlook.

• Now, select the items you want to move to new PST file and drag and drop them into the new file.

Repeat the above steps to create more PST files to move other mailbox items.

Limitations of Manual Methods

The methods discussed above at length are free to use. However, they have certain limitations. These are:

• Required to repeat the process to create multiple PST files, which is time-consuming and tedious.
• Chances of missing mailbox items due to human errors and other technical issues.
• Not suitable for splitting multiple (5+) large PST files at once.
• Work only when Outlook is working and accessible.
• No option to split by size (5GB, 10GB, etc.), year (2024, 2025, etc.), or specific email ID

An Easy Solution to Split PST File – Use a Specialized PST Splitter Tool

For splitting a large PST file into multiple parts based on size, date range, year, email ID, or specific folders — the best option is to use Stellar Splitter for Outlook – a specialized PST splitting tool useful for when you need to split large PST files (≥50 GB in size) into multiple smaller files without any hassle.

Recommended by IT professionals and admins, this powerful tool effortlessly splits your PST file/s into smaller parts based on different criteria, such as size, date, email IDs, or specific folders. It maintains original folder structure and hierarchy in the resultant PST files. Moreover, you can use this tool to split multiple PST files simultaneously.

Here is a quick look at its key features:

• Splits PST files without modifying the structure
• Allows to create batch to automate splitting of multiple PST files in a single operation
• Supports PST files of different versions of Outlook – 2024, 2021, 2019, 2016, 2013, and earlier.

Now, let’s look at the steps to use this software.

• Download and install Stellar Splitter for Outlook on your Windows PC. Launch it.
• The home screen will open. Drag and drop or click on Add PST to select the PST file in the software window.

• On the next screen, choose the Splitting Option - By Date, By Size, or By Mail ID.

Split by Date:

• The "In last" radio option splits the PST file according to months.
• The "Between" radio option splits the PST file according to a specific time period that can be selected using the given Date fields.

Split by Size:

• Use the "Select split size" drop down to choose the size of each split .pst file.

Split by Mail ID:

• A Split PST prompt will appear. Click Yes.

• Select e-mail ids under Mail IDs

• Next, click Browse under the Splitting Options section to choose a destination path to save the split PST files.
• Click on Split and wait for the software to split the selected PST file based on the chosen criteria.

• After the process is complete, you will see the Split Complete dialog box. Click OK.

A Quick Comparison: Manual Methods vs Stellar Splitter for Outlook

Tabulated below is a quick comparison between manual methods and the PST splitter tool.

Conclusion

In this article, we have learned how a large Outlook PST file, approaching the predefined size limit (50GB), can cause various problems, such as slow indexing of items, missing items, and PST file corruption. Hence, it becomes important to split a large PST file into smaller .pst files. You can use the free workarounds – the Import/Export Wizard, the Archive option, or create a new .pst file – to split large PST file. To split multiple or large (>10GB) PST files easily in one go, you can rely on Stellar Splitter for Outlook. It is a specialized tool that offers a fast and secure way to split PST file into multiple files based on different criteria and with complete data integrity.