How to Increase the maximum file size of ost or pst file

The maximum file size of ost or pst is limited by the registry. We can edit the registry settings to increase this file size. In Outlook 2003 and Outlook 2007, the maximum size of a Unicode pst-file has been limited to 20GB. In Outlook 2010, 2013 and 2016, this limit has been set to 50GB.

To increase the file size we have to edit the following 2 registry values.

MaxLargeFileSize - The MaxLargeFileSize registry entry determines the absolute maximum size that both the .pst and the .ost files can grow to. After this maximum size is reached, Outlook does not permit the size of the file to grow beyond this size.

WarnLargeFileSize - The WarnFileSize registry entry determines the maximum data that both the .pst and the .ost files can have. After this maximum data is reached, neither the .pst nor the .ost files are permitted to add any more data. However, the size of the physical file may still increase because of internal processes.

The location of the MaxLargeFileSize and WarnLargeFileSize may change in Domain and Workgroup computers

For Domain Account

You may have to create the registry values if they do not exist. If the registry values do not exist, follow these steps to create them.

§  Click Start, click Run, type Regedit, and then click OK.

§  In the left pane, expand the following registry key:

Outlook 2003
HKEY_CURRENT_USER\Software\ Policies\Microsoft\Office\11.0\Outlook\PST

§  Outlook 2007
HKEY_CURRENT_USER\Software\ Policies\Microsoft\Office\12.0\Outlook\PST

§  Outlook 2010
HKEY_CURRENT_USER\Software\ Policies\Microsoft\Office\14.0\Outlook\PST

§  Outlook 2013
HKEY_CURRENT_USER\Software\ Policies\Microsoft\Office\15.0\Outlook\PST

§  Outlook 2016
HKEY_CURRENT_USER\Software\ Policies\Microsoft\Office\16.0\Outlook\PST

For Workgroup Users

§  Outlook 2003
HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\PST

§  Outlook 2007
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\PST

§  Outlook 2010
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\PST

§  Outlook 2013
HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\PST

§  Outlook 2016
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\PST

Ø  Right click on PST , Click New and click DWORD

Ø  Type name as MaxLargeFileSize

Ø  Repeat the same process and create WarnLargeFileSize

Ø  Right Click MaxLargeFileSize and select Modify. Select Decimal and enter the maximum value of the PST. (For example I entered 71680 to increase the PST size to 70 GB).

Ø  Similarly Enter the value for WarnLargeFileSize. (Here I have entered 66560 to set value to 65GB).

Ø  Click OK and close the registry.