Should I install the 32-bit or 64-bit version of Office/Outlook?

As of the release of Office 2019, Microsoft is now recommending to install the 64-bit version of Office unless you have a specific need which still requires the 32-bit version.

Personally, and mainly from an Outlook perspective, I’ve seen very few instances over the past years where using the 64-bit version of Office would have caused issues, so I’m happy that Microsoft now finally decided that the turning point has been reached.

For Office 2019 and Microsoft 365 Apps (previously known as Office 365), the default for new installations has now been set to 64-bit. Although the considerations for using 32-bit vs 64-bit are the same for Office 2010, 2013 and 2016, the default for new installations of these versions will remain 32-bit for now.

Luckily, it is easy enough to select which bit version you want to install in case you do not want the default one. You can find instructions for this at the bottom of this guide.

Benefits of using the 64-bit version of Office

In general, the main benefit of using the 64-bit version of Office, is that it can use access memory when needed. With the 32-bit version of Office, the application can only use up to 2GB of memory, even when more is available in your computer.

Using the 64-bit version of Office will for instance allow you to work with large data sets like Excel workbooks or Project files that are over 2GB in size.

Similarly, when you are working with large Word documents or PowerPoint presentations that are very rich with multimedia (pictures, videos, complex animations, etc…) or large tables or other embedded objects, the 64-bit version can be of help.

The 64-bit version of Office also offers a security benefit as it always has Hardware Data Execution Prevention (DEP) enabled (although this can be enabled for the 32-bit version as well).

When it comes to Outlook, using the 64-bit version of Outlook does not have any direct benefits. The functionality within Outlook is the same and there is also no (noticeable) performance increase by using the 64-bit edition. There also isn’t a 2GB file size limit for the 32-bit version of Outlook like there is for Excel and Project. The file size limitation in Outlook is determined by whether you are using an ANSI or Unicode formatted pst-file.

When should I consider to still use the 32-bit version?

The main reason for the original recommendation was compatibility with existing add-ins for Office.

For an add-in to work with the 64-bit version of Office, it needs to be recompiled by the developer specifically for the 64-bit version of Office. In some cases the developer also needs to make some specific changes for 64-bit support or needs to wait for specific libraries, that the add-in relies on, to be recompiled for 64-bit. Simply put; It’s a waiting game but nowadays most of the popular add-ins are available for both the 32-bit and 64-bit version of Office.

Popular Outlook add-ins which are not compatible with the 64-bit version of Outlook are the Calendar Printing Assistant and Personal Folders Backup. This last add-in is actually a very old add-in that is also not compatible with the 32-bit version of Outlook 2013 and later and is also not longer being offered by Microsoft (but there is an alternative).

A similar issue exists with other applications that integrate themselves with Office or rely on Office components. They have to be made aware that they can also expect a 64-bit version of Office and of course be compatible with it. When an application integrates with Outlook at MAPI level, this application or component also needs to be 64-bit or the integration is lost.

Specifically for Outlook, there are certain sync applications for (older) mobile phones and Pocket PCs that do not recognize the 64-bit version of Outlook like Windows Mobile Device Manager (WMDC). Unless you are still holding on to such an old mobile device (>9 years old) and are still relying on these synching capabilities, this is not going to be an issue anymore. Even iCloud and iTunes offer 64-bit support for over 5 years now.

If an external application doesn’t support the 64-bit version of Outlook, you usually get an error like:

Either there is no default mail client or the current mail client cannot fulfill the messaging request.

An additional reason to stick with the 32-bit version of Office is that when you are using Compiled Access databases (*.mde and *.accde files), these databases need to be adjusted to support the 64-bit version of Access.

So… Should I use the 64-bit version or not?

Although the list of reasons for the 32-bit recommendation might be long, they however practically all relate to legacy applications.

Considering that the 64-bit version of Office has been first introduced in 2010, if your add-in or app still hasn’t received an update for 64-bit compatibility, it probably never will. It is best to check with the vendor or developer whether the add-in or app is actually still supported and if not, it is probably best to look for a 64-bit alternative either way.

When none of the reasons to stick with 32-bit apply to you, then using the 64-bit version of Office isn’t going to cause a problem for you. As mentioned before; Pretty much all supported add-ins and applications are fully compatible with the 64-bit version of Office and Outlook.

A small downside that is good to keep in mind though is that the 64-bit version of Office can take up between 5% and 20% more disk space when compared to the 32-bit version. Some of this is caused by the fact that certain components also still install the 32-bit version next to their 64-bit version counterpart for compatibility reasons. In reality, this comes down to a 300 – 500MB larger footprint, so unless you are using a really small disk (32GB or less), this might hardly be a consideration.

Installing or downloading the 64-bit version of Office

When you start Setup from an installation medium for Office 2016 or earlier that has both the 32-bit and the 64-bit version on it, you’ll be installing the 32-bit version of Outlook/Office by default.

The reverse applies to Office 2019; When the installation medium contains both the 32-bit and 64-bit version, the 64-bit version will be installed.

To install the other bit version of Office, close the current Setup window and browse to the installation source (for instance your DVD-drive). Here you’ll find one of the following;

• Folders called x64 and x86
  Open the x64 folder if you want to install the 64-bit version or open the x86 folder to install the 32-bit version. Double click the setup.exe file located in this folder to install Office.The setup process is the same for both the 32-bit as the 64-bit version of Office/Outlook.
• Folder called office
  Open the office folder and double click setup32.exe to install the 32-bit version or double click setup64.exe to install the 64-bit version of Office.

If you currently don’t have a 32-bit or 64-bit installation media, depending on your edition of Office, you can download the correct installation setup from the following links:

• Download: Microsoft 365 for Home
  Click on “Install Office”, the “Other options”, and finally use the “Version” dropdown list to select 32-bit or 64-bit. The default is 64-bit.
• Download: Microsoft 365 for Business and Enterprise
  The “Version” dropdown list should already be set to 64-bit but you can set it to 32-bit if needed.
• Download: Office 2019 (Retail)
  Click on the “Install” link below the Office 2019 listing and in the dialog that opens, click the “Other options” link to see the 32-bit version.
• Download: Office 2016 (Retail)
  Click on the “Install” link below the Office 2016 listing and in the dialog that opens, click the “Other options” link to see the 64-bit version.
• Download: Office 2013
  Supply your Product Key, go through the wizard and select to download the 64-bit version.
• Download: Office 2010
  Supply your Product Key, go through the wizard and select to download the 64-bit version.

You can use the same license key as the 32-bit version. No license key is needed at all for the Office 365 versions as you’ll activate that by logging on to Office with your Microsoft Account or Work Account.

Make sure you uninstall all 32-bit Office versions (including older ones) and other 32-bit applications of Office before you start. So if you are for instance also using Visio or Project, you also need to install the 64-bit version of these applications.

Check whether I have the 32-bit or 64-bit version installed

You can see whether you are using the 32-bit or 64-bit version of Office by opening the About dialog box of Outlook (or any other Office application of course);

• Outlook 2010
  File-> Help-> About-> Additional Version and Copyright Information
• Outlook 2013 / 2016 / 2019 / Microsoft 365
  File-> Office Account-> About Outlook

At the top of the About dialog, you’ll see the current build number of the application and MSO appended with either 32-bit or 64-bit.