Tip: How to increase (maximize) Outlook 2003, 2007, 2010 & 2013 PST file size limit

Last updated on May 8th, 2017

All versions of Microsoft Outlook use (by default) a single file to store all the information included on the Outlook program, like Emails, Contacts, Tasks and Calendar. This file by default is named “Outlook.pst” (the “PST” extension means “Personal Data Folder”) and has a default maximum size limit depending on the Outlook version. That means that over the default limit, Outlook cannot store (cannot receive new e-mails) and displays the following "0x8004060C" error message during send/receive procedure: "Task ‘mail@server.com – Receiving’ reported error (0x8004060C): ‘The message store has reached its maximum size. To reduce the amount of data in this this message store, select some items that you no longer need, and permanently (SHIFT + DEL) delete them".

Up to Outlook 2002 version, the default size limit for the “Outlook.pst” file was about 2GB, because the “Outlook.pst” file was created using the ANSI format and the ANSI format prevents the “Outlook.pst” file to be increased over 2GB (1.933 GB).

In the latest versions (Outlook 2003, 2007, 2010 & 2013), the “Outlook.pst” is UNICODE formatted and the default size limit for “Outlook.pst” is increased. Specifically, for Outlook 2003 & 2007,  the default size limit for PST file (or OST if you use an Exchange server for your e-mails) is 20GB and for Outlook 2010 & 2013 versions, the default size limit is 50GB.

Although this size is enough for most users, there is the need to maximize this limit for users who receive a large number of emails  This tutorial shows how to increase the default size limit in Outlook 2003, 2007, 2010, 2013 @ 2016 Versions.

How to increase (maximize) Outlook 2003, 2007, 2010, 2013 & 2016 PST file size

Step 1: Open Registry Editor.

How to open Registry Editor:

1. Open “Run” command and in the search (run) box, type “regedit” and press “Enter”.

Windows XP:

Press “Start” and choose “Run


Windows 7, Vista

Press “Start” and click on the “search”box.



Windows 8:

Right-click on the bottom left corner and select “Run”.



Step 2: Modify Outlook PST size limit through registry.

1. Inside Registry editor, look at the left pane and under “Computer”, navigate to the following registry path according to your Outlook version:

For single users:

  • Outlook 2016: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\PST
  • Outlook 2013: HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\PST
  • Outlook 2010: HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\PST
  • Outlook 2007: HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\PST
  • Outlook 2003: HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\PST

For Administrators: (Via Group Policy)

  • Outlook 2016: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\PST
  • Outlook 2013: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\15.0\Outlook\PST
  • Outlook 2010: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\14.0\Outlook\PST
  • Outlook 2007: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\12.0\Outlook\PST
  • Outlook 2003: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\11.0\Outlook\PST



Note: IF the PST key doesn't exist under Outlook key, you have to create it manually. To do this:

a. Right-click on the Outlook key and from the menu that appears, choose: NewKey.
Give at the new key the name: PST.


2. Double click at PST key and look at the right pane to find these two (2) values: *

  1. MaxLargeFileSize
  2. WarnLargeFileSize


Note: If the above values cannot be found in the registry, then you have to create them manually. To do this:

a. Right-click on the right pane and from the menu that appears, choose: New > DWORD Value


b. Give at the new value the name:  MaxLargeFileSize


c. Repeat the above procedure (2a) and create a new DWORD value with name: WarnLargeFileSize



3. Double click at “MaxLargeFileSize” value, choose “Decimal” and in the value data type the new file size in Megabytes (MB). *


  • In Outlook 2003 & 2007 the default Outlook PST size limit is 20GB, so you have to specify a size over 20GB.
  • In Outlook 2010 & 2013 the default PST size limit is 50GB, so you must specify a size over 50GB.

Note: 1GB=1024MB, 30GB=30720MB, 50GB=51200MB, 70GB=71680MB, 100GB=102400MB

In our example we are going to increase the Outlook PST size limit to 30GB (Outlook 2003 & 2007)

MaxLargeFileSize[5] value data


4. Then double click at “WarnLargeFileSize” value, choose “Decimal” and in the value data, type the new warning file size in Megabytes (MB). *

Attention: This value must be set at least 95% of the MaxLargeFileSize value (MaxLargeFileSize X 95%)

* In our example: 30720 X 95% = 29184.


5. Close Registry Editor.

You 're done!

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