Since Office 2010, Microsoft has offered a 32-bit install and a 64-bit Office install. You might think the 32-bit version was for 32-bit Windows and the 64-bit for 64-bit windows, but 64-bit windows can run actually run 32-bit Office fine,
It was initially recommended to run 32-bit Office as all the Office plugins were typically written for 32-bit, you were only recommended to run 64-bit if you needed to address a lot of RAM, for example running large spreadsheets. The default Office 365 click to run install was indeed 32-bit regardless of your OS version, until now. from now mid-Jan 2019 forward both Office ProPlus (the continuously updating subscription version from Office 365) and Office 2019 (the version you buy “in a box” but also actually click to run).
Oddly the Office 365 message centre message was published, then disappeared for a while, but now is back.
The benefits of using a 64-bit Windows and Office are most apparent when you have a large amount of random access memory (RAM) installed on your computer, typically 4 GB of RAM or more. 64-bit operating system can handle large amounts of memory, so a 64-bit system can be more responsive when running several programs at the same time and switching between them frequently.
Some examples of where 64-bit Office is particularly useful:
- You’re working with large data sets, like enterprise-scale Excel workbooks with complex calculations, many pivot tables, data connections to external databases, Power Pivot, 3D Map, Power View, or Get & Transform. The 64-bit version of Office may perform better in these cases. See, Excel specifications and limits, Data Model specification and limits, and Memory usage in the 32-bit edition of Excel.
- You’re working with extremely large pictures, videos, or animations in PowerPoint. The 64-bit version of Office may be better suited to handle these complex slide decks.
- You’re working with files over 2 GB in Project, especially if the project has many sub-projects.
- You’re developing in-house Office solutions like add-ins or document-level customization. Using the 64-bit version of Office lets you deliver a 64-bit version of those solutions as well as a 32-bit version. In-house Office solution developers should have access to the 64-bit Office 2016 for testing and updating these solutions.
- You’re working with the Large Number data type in Access, and while this data type is supported by 32-bit Access, you may see unexpected results when executing code or expressions that use native 32-bit VBA libraries. 64-bit VBA provides the LongLong data type which fully supports large numbers. For more information, see Using the Large Number data type.
We also saw a recent issue with Skype for Business screen sharing where high resolution displays were causing issues with the 32-bit version as high res screen sharing needs a big memory buffer.
This shouldn’t be a big deal for most people, but enterprises that have been running 32-bit Office may want to test all their plugins on 64-bit Office. You can still install 32-bit Office if you prefer, but you’ll have to explicitly select it.
Office 365 Portal Message: https://portal.office.com/adminportal/home#/MessageCenter?id=MC171479