With 64-bit apps, you have up to 128 TB of virtual address space which the app and any add-ins running the same process can share. While 32-bit applications can work with add-ins, they can use up a system's available virtual address space.

You're using add-ins with Outlook, Excel, or other Office apps. See Excel specifications and limits, Data Model specification and limits, and Memory usage in the 32-bit edition of Excel. The 64-bit version of Microsoft 365 may perform better in these cases. 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. Therefore, if your scenarios include large files and/or working with large data sets and your computer is running 64-bit version of Windows, 64-bit is the right choice when:

Also, 64-bit applications can access more memory than 32-bit applications (up to 18.4 million Petabytes). Reasons to choose the 64-bit versionĬomputers running 64-bit versions of Windows generally have more resources such as processing power and memory, than their 32-bit predecessors. If you're still not sure which version, 32-bit or 64-bit is a better choice for you, see the section below. See “Office (64-bit or 32-bit) couldn’t be installed” error.

The same is true if you installed the 32-bit version, but want to install the 64-bit version. Important: If you install the 64-bit version, but want the 32-bit version instead, you must first uninstall the 64-bit version before installing the 32-bit version.

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