Since the first release of Outlook, Microsoft has released many updates and service packs.

The following list is an overview of the available public Microsoft Outlook builds. The list also includes useful information which should help an administrator to determine the build info of a client that is logged-on to the Microsoft Exchange Server.

With the release of Office 2016 and four different branches on four different release schedules, having an older version number doesn't necessarily mean your Office isn't updated. It can be up to four months before everyone reaches a milestone. Office 365 client update branch releases contains the a list of updates for the different branches.

Office 2016 version and build numbers are also available at Version and build numbers of update channel releases

To check the Outlook build number in Outlook 2013 and newer, click on the File tab, then Office Account. Click About Outlook to see the full-sized About Microsoft Outlook dialog.

In Outlook 2010, Help is on the File tab. If you want to see the classic version dialog, click the link for Additional Version information to see the classic dialog. In older versions, click on Help, About.

Outlook: 2003 | 2007 | 2010 | Outlook for Mac
Exchange version numbers are here

Office 2016

Beginning with Office 2016, updates are released to different groups at different time: Insider, First Release for Current Branch, Current Branch, Current Branch for Business. Insider gets pre-release updates frequently (basically, beta testers), First Release gets released updates ahead of other subscribers (Current Branch) monthly, while Current Branch for Business gets updates 4 times a year (and security updates monthly). Confusing right?

In plain English, the typical Office 365 Consumer is in the First Release, while small business subscribers are in Current Branch. In many cases, the time difference between updates released to First Release and Current Branch will be measured in days. If you joined the Insider program, you'll get updates more often.

Trying to keep up with the version numbers is a nightmare and hopefully Microsoft will keep their lists updated.

Version numbers of update branches for Office 365 clients

List of all updates for Office 2016 subscription, by year, month, and application. Although the article is targeted to business subscriptions, it applies to consumer subscriptions too. Office 365 client update branch releases

Update Office 2013 or Office 365

Office 365 subscribers will be automatically upgraded to the next version of Office. (The upgrade can be delayed for up to one year.)

Beginning with Office 2013, most installations are "click to run" and updates are installed (usually automatically) from the Office update server. Anyone using the "click to run" installation will not use an update file.

Outlook 2007 is Version 12.0. Beginning with Outlook 2007, the versions reported in Outlook and in the Exchange administrator are identical.

LifeCycle

The following are the "end of life" dates for the different Outlook versions.

Note that End of Life means Microsoft will not support it, nor will they release updates for it. Office will continue to work on supported versions of Windows.