MS Office: 32 bit vs 64 bit

An advantage of 64-bit Office is that larger file sizes are supported.

Also, workbooks of the 32-bit version of Excel 2010 can have «only» up to 255 sheets.

A 32-bit Excel installation can address only up to 2 GB memory. This might impact the SSAS Vertipaq Engine, which is used by Power Pivot, negatively.

Some disadvantages of 64-bit Office include:

• Some features that are present in 32-bit Office are missing in 64-bit Office (notably: The legacy equation editor of Word and Word Add-in Libraries (WLLs)).
• Rendering graphics might be subject to performance degradation because 64-bit does not support MMX.
• When porting or migrating Visual Basic for Applications from 32-bit to 64-bit, declare statements need to be updated (See ptrSafe)
• ActiveX and COM add-ins that were written for 32-bit environments won't run in 64-bit Office. Similarly, In-place OLE activation might not work.
• Access files with the extensions .mde, ade and .accde that have had their source code removed cannot be run on 64-bit Office
• MAPI applications need to be rebuilt.

Because the disadvantages in most cases outweigh the advantages, Microsoft recommends for most users to use 32-bit Office.

A 64-bit version of Office runs on a 64-bit version of Windows only.

Microsoft does not support the installation of both a 64-bit and 32-bit version of Office on the same machine. Thus, in order to change the Office bitness, the «old» version needs to be uninstalled.

Some applications prevent the installation of a 64-bit Office. These applications include

• Microsoft Office Excel Viewer
• Access database engine of Access 2013
• Compatibility Pack for the 2007 Office system