Choose between the 64-bit or 32-bit version of Office

I know which version I want. How do I install it?

The 64-bit version of Microsoft 365 is automatically installed unless you explicitly select the 32-bit version before beginning the installation process.

To install either the 32 or 64-bit version of Microsoft 365, Office 2021, or Office 2019, follow the steps in Install Office on a PC.

If you're still not sure which version, 32-bit or 64-bit is a better choice for you, see the section below.

Reasons to choose the 64-bit version

Computers running 64-bit versions of Windows generally have more resources such as processing power and memory, than their 32-bit predecessors. Also, 64-bit applications can access more memory than 32-bit applications (up to 18.4 million Petabytes). 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:

• 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 Microsoft 365 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 using add-ins with Outlook, Excel, or other Office apps. While 32-bit applications can work with add-ins, they can use up a system's available virtual address space. 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. With 32-bit apps, you might get as little as 2 GB of virtual address space which in many cases isn't enough and can cause the app to stop responding or crash.

• You’re working with extremely large pictures, videos, or animations in PowerPoint. The 64-bit version of Microsoft 365 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 Microsoft 365 solutions like add-ins or document-level customization. Using the 64-bit version of Microsoft 365 lets you deliver a 64-bit version of those solutions as well as a 32-bit version. In-house Microsoft 365 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.

Reasons to choose the 32-bit version

The following computer systems can only install 32-bit Microsoft 365. Check your Windows version.

• 64-bit Windows 10 with ARM-based processor

• 32-bit operating system with an x86 (32-bit) processor

• Less than 4 GB RAM

IT professionals, and developers in particular, should also review the following situations where the 32-bit version of Microsoft 365 is still the best choice for you or your organization.

• You have 32-bit COM Add-ins with no 64-bit alternative. You can continue to run 32-bit COM add-ins in 32-bit Microsoft 365 on 64-bit Windows. You can also try contacting the COM Add-in vendor and requesting a 64-bit version.

• You use 32-bit controls with no 64-bit alternative. You can continue to run 32-bit controls in 32-bit Microsoft 365 like Microsoft (Mscomctl.ocx, comctl.ocx), or any existing 3rd-party 32-bit controls.

• Your VBA code uses Declare statements Most VBA code doesn’t need to change when using in 64-bit or 32-bit, unless you use Declare statements to call WindowsAPI using 32-bit data types like long, for pointers and handles. In most cases, adding PtrSafe to the Declare and replacing long with LongPtr will make the Declare statement compatible with both 32- and 64-bit. However this might not be possible in rare cases where there is no 64-bit API to Declare. For more information about what VBA changes are needed to make it run on 64-bit Microsoft 365, see 64-Bit Visual Basic for Applications Overview.

• You have 32-bit MAPI applications for Outlook. With a growing number of 64-bit Outlookcustomers, rebuilding 32-bit MAPI applications, add-ins, or macros for 64-bit Outlook is the recommended option, but if needed you can continue to run them with 32-bit Outlook only, as well. To learn about preparing Outlook applications for both 32-bit and 64-bit platforms, see Building MAPI Applications on 32-Bit and 64-Bit Platforms and the Outlook MAPI Reference.

• You’re activating a 32-bit OLE server or object. You can continue to run your 32-bit OLE Server application with a 32-bit version of Microsoft 365 installed.

• You need 32-bit Microsoft Access .mde, .ade, and .accde database files. While you can recompile 32-bit .mde, .ade, and .accde files to make them 64-bit compatible, you can continue to run 32-bit .mde, .ade, and .accde files in 32-bit Access.

• You require Legacy Equation Editor or WLL (Word Add-in libraries) files in Word. You can continue to use Legacy Word Equation Editor and run WLL files in 32-bit Word.

• You have an old embedded media file in your PowerPoint presentation with no available 64-bit codec.

Ready to install?

To install either the 32 or 64-bit version of Microsoft 365, Office 2021, or Office 2019, follow the steps in Install Office on a PC.