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Increase Outlook Data (.pst & .ost) File Size Limit

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Written By Kumar Raj
Anuraag Singh
Approved By Anuraag Singh
Published On August 11th, 2022
Reading Time 8 Minutes Reading

There are various cases when you need to increase Outlook PST file size limit than default size available. In case, if you receive lots of emails a day with larger attachments, it can result in size limit issues. Here in this blog, you can see how to configure the size limit for (.pst) and (.ost) files in Outlook using registry entry.

Additional Point to be Noted:

If you are using SysTools PST Merge Tool to merge large Outlook PST data files, then follow these steps for mandatory. There is the chance for the resultant PST file generated is larger than the default PST file size of the Outlook version you use. And this may result in the corruption of the file while you try to import that PST data file in the Outlook account. Increase the Outlook PST file size limit using Registry entries; go through the upcoming section thoroughly.

Microsoft Outlook 2003, 2007 versions, the default maximum recommended Outlook PST / OST file size is 20 GB and for Outlook 2002 and below version, the default maximum recommended size was 2 GB. And in the latest versions like Outlook 2010, 2013, 2016, 2019, the default maximum recommended size for OST / PST file is 50 GB.

This article describes how to increase Outlook data file size using Outlook Registry. The following four registry entries allow to limit the size of Outlook .pst and .ost files:

  1. The MaxFileSize registry entry
  2. The WarnFileSize registry entry
  3. The MaxLargeFileSize registry entry
  4. The WarnLargeFileSize registry entry
  • The MaxFileSize registry entry: It determines an absolute maximum size for .pst and .ost files, up to which it can grow. The Outlook does not permit the size of the data file to grow beyond this maximum size.
  • The WarnFileSize registry entry: It determines the maximum data an Outlook data file can have. When this maximum data is reached, the Outlook .pst or .ost files are not permitted to add any more data. But, there can be an increase in the physical file size because of internal processes.
  • The MaxLargeFileSize registry entry: To set the maximum size up to which Outlook data file can be expanded (only for UNICODE files).
  • The WarnLargeFileSize registry entry: To set the maximum allowable data for Outlook data (PST / OST) file (only for UNICODE files).

Size Limit for MS Outlook Data Files

Here in the below-given table, the MaxLargeFileSize and WarnLargeFileSize registry entry state to a UNICODE formatted files. The MaxFileSize and WarnFileSize registry entry state to ANSI formatted files.

For Outlook 2016, 2013, and 2010

Name Type Valid Data Range Default
MaxLargeFileSize REG_DWORD 0x00000001 – 0x0000C800 0x0000C800 51,200 (50 GB)
WarnLargeFileSize REG_DWORD 0x00000000 – 0x0000BE00 0x0000BE00 48,640 (47.5 GB)
MaxFileSize REG_DWORD 0x001F4400 – 0x7C004400 0x7BB04400 2,075,149,312 (1.933 GB)
WarnFileSize REG_DWORD 0x00042400 – 0x7C004400 0x74404400 1,950,368,768 (1.816 GB)

For Outlook 2007 and 2003:

Name Type Valid Data Range Default
MaxLargeFileSize REG_DWORD 0x00000001 – 0x0000C800 0x00005000 20,480 (20 GB)
WarnLargeFileSize REG_DWORD 0x00000000 – 0x0000BE00 0x00004C00 19,456 (19 GB)
MaxFileSize REG_DWORD 0x001F4400 – 0x7C004400 0x7BB04400 2,075,149,312 (1.933 GB)
WarnFileSize REG_DWORD 0x00042400 – 0x7C004400 0x74404400 1,950,368,768 (1.816 GB)

Increase Outlook (PST & OST) File Size Limit

As we have discussed, the size restrictions on Outlook data (.pst and .ost) files can be configured through the registry. So let us see how to increase the Outlook data file size limit. Also note that, depending on the version of Microsoft Outlook, registry keys used are also different.

Now see the path of policy location and user preference location for the registry entries in the Registry Editor concerning each MS Outlook version.

NOTE: Although the Registry path says “PST”, it also applies to OST files.

Outlook Version Policy location for registry entries in Registry Editor User preference location for registry entries in Registry Editor
Outlook 2016 HKEY_CURRENT_USER\ Software\Policies\Microsoft\Office\ 16.0\Outlook\PST HKEY_CURRENT_USER\Software\ Microsoft\Office\16.0\Outlook\PST
Outlook 2013 HKEY_CURRENT_USER\ Software\Policies\Microsoft\Office\ 15.0\Outlook\PST HKEY_CURRENT_USER\Software\ Microsoft\Office\15.0\Outlook\PST
Outlook 2010 HKEY_CURRENT_USER\ Software\Policies\Microsoft\Office\ 14.0\Outlook\PST HKEY_CURRENT_USER\Software\ Microsoft\Office\14.0\Outlook\PST
Outlook 2007 HKEY_CURRENT_USER\ Software\Policies\Microsoft\Office\ 12.0\Outlook\PST HKEY_CURRENT_USER\Software\ Microsoft\Office\12.0\Outlook\PST
Outlook 2003 HKEY_CURRENT_USER\ Software\Policies\Microsoft\Office\ 11.0\Outlook\PST HKEY_CURRENT_USER\Software\ Microsoft\Office\11.0\Outlook\PST

Important Note: In the upcoming section, we have explained the steps to modify the Outlook registry. Make sure that you follow the steps very carefully. Because severe problems might follow if the registry is modified incorrectly.

Tip: For additional safety, keep a backup of the registry before you modify it. So, you can restore the registry if an error occurs.

Steps to Increase Outlook Data File Size Limit

Follow the steps to modify the registry to increase the size limit of your Outlook PST or OST files.

  1. Click Start, and then click Run.
  2. A box will be opened, type regedit, and then click OK.
  3. Now in the left pane, expand My Computer >> expand HKEY_CURRENT_USER.
  4. Then expand Software >> Policies >> Microsoft >> Office.
  5. Now Expand the version number with respect to the Outlook version you use. Expand accordingly as given the below table.
11.0 Outlook 2003
12.0 Outlook 2007
14.0 Outlook 2010
15.0 Outlook 2013
16.0 Outlook 2016
16.0 Outlook 2019
  1. Then expand Outlook and right click on PST.
  2. And now right-click on MaxFileSize / WarnFileSize / MaxLargeFileSize / WarnLargeFileSize in the right pane (depending on the registry entry added in your Outlook account).
  3. Now click on Modify, and then type the value in the Value data box according as given from the above table.
  4. Click OK.

Note: If registry values do not exist (if not added already), then you have to create it by yourself. Follow the below-given steps carefully.

Steps to Configure Size Limit for (.pst) and (.ost) Files in Outlook

  1. Click Start, and then click Run.
  2. Type regedit, and then click OK.
  3. In the left pane, expand the following registry key location according to your MS Outlook version:
Outlook Version Policy location for registry entries in Registry Editor
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
  1. Now right-click on Outlook >> expand New, and then click on Key.

outlook registry

  1. Type in PST >> press on ENTER.

outlook registry pst

  1. Now right click on PST >> click on New >> then click on DWORD value.

outlook registry dword

  1. Now type in MaxFileSize >> then press on ENTER twice.

outlook registry dword type

  1. Now in the Edit DWORD Value window, first choose Decimal option in Base, and provide the value in the Value data box. Then click on OK.

outlook registry dword value entry

For example:

  • 1GB = 1*1024*1024*1024byte = 1073741824
  • 1MB = 1*1024*1024byte = 1048576
  • 1KB = 1*1024byte

Note: Repeat steps 3 through 8 to create other DWORD value like WarnFileSize / MaxLargeFileSize / WarnLargeFileSize. Then close the registry.

Points to Remember

  • The values between the MaxFileSize and the WarnFileSize registry entry and the values between the MaxLargeFileSize and the WarnLargeFileSize registry entry must be at least 5 percent (%). So this increased Outlook data file size will not hinder the internal processes to continue.
  • The next point is, the configured value will be ignored to prevent corruption if the value of the MaxFileSize registry entry ever exceeds the 2 GB limit (for ANSI Types PST or OST files).
  • The default value added for the WarnFileSize registry entry must only be 95% of the MaxFileSize registry entry for a UNICODE file (PST / OST files).

It is possible to set the UNICODE limits beyond the values that are listed in the above table. But, we do not recommend doing the same, because it may affect the Outlook performance.

What if PST File Get Corrupted?

The Microsoft Outlook PST file get damaged and becomes inaccessible due to corruption problems. One major reason for PST file corruption is overwriting a PST file due size limitation problem. This problem was hugely affected in earlier Outlook version PST files. But in latest versions also, users face same problem. The only way to fix a corrupted PST file is to repair it. SysTools has leading solution for resolve Outlook PST file issues. The Outlook PST Recovery software can repair highly corrupted data files. Download the software, scan and repair your Outlook PST file in few simple steps.

A PST data file can be corrupted by multiple reasons. The oversized PST file issue is only one among them. But the software suggested above a help to fix PST data issues irrespective of the cause. It is an all-in-one solution for MS Outlook users.

  author

By Kumar Raj

A versatile writer with the vast knowledge of technology helps to reduce the gap between a user and technology. Provides easy and reliable ways to resolve multiple technical issues, which users encounter in their day-to-day life.