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Written By Rohan Wiese
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Approved By
Shivam Rathore -
Updated on February 9th, 2026
There are several reasons why your OST file increases the file size, including:
All of these reasons can increase your OST file size.
Once your OST file becomes oversized, you will face multiple problems, such as:
The size of the OST file depends on the version of MS Outlook that you are using.
If the size reaches the limits, it’s need to take action and manage your file.
There are multiple manual methods available to fix the oversized OST file. So that you can prevent your data from being inaccessible or prone to corruption. You can apply these basic methods to reduce the size of a large OST file in Outlook, like:
Let’s explore all the methods in detail.
When your OST file is too large, you need to decrease its size. Here is how you can perform it to decrease the size of the OST file:
You can decrease the size by removing all the unnecessary information from your OST file. Continue with the steps below:
Sometimes, archiving old emails can reduce the size of the OST file. Changing the location of the archive in your system might be beneficial to reduce OST size.
Shared folders in Outlook can quickly add to the size of your OST file, which leads to Outlook performance issues. To improve Outlook’s speed, you can turn off the sync feature for shared folders by following these simple steps:
While manual methods can sometimes fix minor issues with Outlook OST files, they come with several limitations. Here are the key drawbacks you should be aware of:
To recover from these limitations, you can use the professional tool and get a hassle-free solution.
The Aryson OST Splitter Tool is helpful to decrease the size of the OST file. It splits your oversized OST files into smaller parts based on Size, Date, Sender, and Folder. With this top-notch utility, you can split a single or multiple OST files simultaneously without any hassle. You can access all your important emails, contacts, events, and other data without relying on MS Outlook. Additionally, it offers a simple interface, which is easy to understand and operate even for non-tech users.





If your OST file becomes too large, the best solution is to split the OST file into several smaller parts. This process can be done by using an effective and efficient OST Splitter Tool. It offers several developed features or filters, like:
Above, we shared different methods to reduce the size of the OST file. It protects your Outlook from slowing down when the OST file too large. You can use either the manual method or a splitter tool to decrease the OST size. However, we recommend using the professional tool as a good choice. It saves your time, efforts, and offers a hassle-free result without data loss. Moreover, the trial (demo) version of this software is public to estimate its performance and familiarity.
Ans: Follow the steps below to check the size of the OST file:
✅ Open Outlook and go to the File tab.
✅ Click on Account Settings, then select Account Settings again.
✅ In the Data Files tab, you’ll see a list of your data files along with their sizes.
Ans: If your OST file exceeds the maximum size limit for your Outlook version. You can use either the manual method or an OST Splitter Tool to divide the file into smaller parts.
Ans: No, using an OST Splitter Tool preserves the structure and formatting of your data during the splitting process. It ensures that your Outlook data remains intact.
Ans: Yes, if the OST file becomes too large, Outlook may slow down or stop responding entirely. This is because the program struggles to process and load such a heavy data file.
About The Author:
Rohan Wiese is a Technical Writer at Aryson Technologies. He is an expert Email Forensic, Cloud Computing, and a passionate nerd with over 10 years of experience in technical content writing. He writes about Cloud Migration, Database Recovery, Email Backup, Windows, Mac, and Tech.
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