How to Increase Outlook Mailbox Size in Outlook 2019, 2016?

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  • Published on
    June 27th, 2017
  • Updated on
    February 11, 2022
  • Read Time
    6 minutes
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Summary:-If you’ve been using Outlook client since long, you must know that the PST files have size limitation issue. You just can’t store more content into a PST file than its maximum size limit. If you’re using any older version of Outlook client, such as 2002 or earlier, you have a maximum size of 2 GB. Or if you’re using Outlook 2003 or any later version including the latest 2016, you get enough storage space, i.e. 20 GB to 50 GB. But sometimes it’s not that enough especially when you’re sending and receiving thousands of email messages each and every day. Dealing with such size limitation issue is very challenging for Outlook users. In this post, I’ll show you how to increase Outlook mailbox size so that you can get enough storage space.

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What are the Types of PST Files?

Microsoft Outlook client creates Outlook data file, called PST or personal storage table, on a local computer system. It saves the PST files in two different formats: ANSI and Unicode. In Outlook 2002 and earlier versions, PST files are saved in ANSI format. In Outlook 2003 and later versions including the latest 2016, PST files are saved in Unicode format. Size limitation is the only difference between these two formats. An ANSI PST file can only store up to 2 GB of mailbox content. On the other hand, a Unicode PST file can store 20 to 50 GB mailbox content. In Outlook 2003, 2007 & 2010, the maximum size limitation is 20 GB. And in Outlook 2013 & 2016, the maximum size limitation is 50 GB. Now it’s clear that Unicode PST file provides you more storage space than ANSI PST.

These days, most Outlook users are using the latest versions. It means most of the Outlook users are using Unicode PST file format. Though it provides you with enough storage space, sometimes you may face size limitation issues. If the size of the PST file grows and reaches its maximum size, it may cause some serious problems for Outlook users. You’ll notice that the Outlook client starts hanging or crashing frequently. Sometimes you can face even the worst situation which is corruption. An oversized PST file is always prone to corruption. Being oversized means the PST file has reached or exceeded its maximum size limitation.

Reasons of Outlook Mailbox Corruption

Corruption is not less than a nightmare for Outlook users. It can cause permanent data loss situations. In the case of minor corruption, you can use the scanpst.exe utility to repair the PST file. But if corruption is severe, the Inbox Repair tool can’t help you. You have to use a professional recovery tool that’ll cost you a lot of money. How about this if I show you an easy manual trick to increase Outlook mailbox size? By using that trick, you can easily increase PST file size without causing any alteration or damage.

How to Increase Outlook Mailbox Size Limit?

I’ve heard this question thousand times so far. Most Outlook users stuck with PST file size limitation issues. They want to increase Outlook mailbox size limit so that they can store more mailbox content. If you’re using Outlook 2003, Outlook 2007, Outlook 2010, Outlook 2010 or Outlook 2016, you should definitely try the manual trick I’m sharing below. You should use Windows Registry Editor. There you can define the PST file size limit as per the Outlook version you’re using. Just follow these simple steps:

Open Registry Editor

Step 1: Press Win + R on your desktop screen. Now enter “regedit” in the search box and click regedit.exe on your system

This will take you to the Registry Editor.

Now modify PST mailbox size

Step 2: You’ll see a tree structure under Computer on Registry Editor window. In the list, you’ll see HKEY_CURRENT_USER to use registry editor

Expand it by clicking it once.

Step 3: Now you need to navigate to the following registry path according to your Outlook version.

For single users

  • For Outlook 2003 users, navigate to
  • For Outlook 2007 users, navigate to
  • For Outlook 2010 users, navigate to
  • For Outlook 2013 users, navigate to
  • For Outlook 2016 users, navigate to

For administrators

  • For Outlook 2003 users, navigate to
  • For Outlook 2007 users, navigate to
  • For Outlook 2010 users, navigate to
  • For Outlook 2013 users, navigate to
  • For Outlook 2016 users, navigate to

Step 4: Once you’ve reached to the entry PST in the tree-structure, you’ll see something this:

how to use registry editor

Step 5: If you can’t see the following two values there, you have to create them manually:

  • MaxLargeFileSize
  • WarnLargeFileSize

Step 6: Just right-click on the blank space. Point to New > DWORD (32-bit) to use registry editor

Note: If you’re using Outlook 64-bit version, you should choose QWORD (64-bit) Value.

Step 7: Give this entry a name: to use registry editor

Step 8: Again, right-click on the blank space. Point to New > DWORD (32-bit) Valuehow to use registry editor

Step 9: Give this entry a name: to use registry editor

Once you’ve created these two values, you have to define their values. How will you do that?

Step 10: First double-click to use registry editor

Now enter the Value data and define the Base type:

  • Define the value data in MB. Make sure it should be more than the maximum size of your PST file. Since I’m using Outlook 2010 and I want 50 GB PST file size, I’ll enter 51200, i.e. 50 GB=51200 MB.
  • Choose Decimal as the base type, and click OK to save it.

Step 11: Now double-click to use registry editor

Now again enter the Value data and define the Base type:

  • This time enter a value which must be at least 95% of the MaxLargeFileSize value. For e.g. 51200 x 95%= 48640.
  • Choose Decimal as the base type, and click OK to save it.

Step 12: Now close the Registry Editor.

The task of “increase Outlook mailbox size” has been successfully completed.

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