I have Win 7, not sure what build I have.

I have Win 7, not sure what build I have.

There are actually several ways of finding out what build number you have on your Windows 7 operating system. It's a combination of using Windows built-in tools and/or running some simple apps as backup when all else fails. I'll try to outline each one below, hoping that one of them answers your question.

• Click on Start, locate the "Search programs and files" box at the bottom part, and type System Information. It should come up with search results for "Programs" and "Control Panel". An application aptly named "System Information" will be on top of the results.
• Click "System Information" and wait for the application to show. On the "System Summaries" tab, information pertaining to hardware and software configurations are shown. The tab shows OS Name and more importantly Build Number on the right side of the information. That's It!
• Press "Win + R" on your keyboard (Where "Win" is the windows logo key").
• Enter "winver" on the run command window.
• Voila! "About Windows" shows your Windows Version as well as the Build Number.
• Open Microsoft Word 2010. 
• Click on "File", then "Help". Product information for Microsoft Office on the right side should appear.
• Click on "Additional Version and Copyright Information". A new window showing "About Microsoft Word" should pop-up.
• Look for the "System Info" box on the lower right hand corner and click on it. "System Information" application from suggestion 1 will show necessary Windows 7 build number as expected.

NOTE: Other versions of Office also contain the Windows Build Number.

• Unknown to many, the Windows Registry Editor contains information on what Windows Build number there is. Here's how to do it. I attached a word of warning with using it, since regedit makes system changes and any untoward incident could render your system unbootable. 

CAUTION: Windows Registry is a system tool with the capacity to make changes to the system. Be careful when opening/running this application.

• Click "Start", type "Regedit" on the "Search Programs and Files" box.
• Locate the HKEY_LOCAL_MACHINE tab and navigate the drop down menu till you get to HKEY_LOCAL_MACHINESoftwareMicrosoftWindows NTCurrentVersion.
• You should see "CurrentBuildNumber" on the right side. Please remember not to make any changes to the data on the right side. Doing so may cause changes and alterations to the original settings. Simply close regedit after viewing the build number.
• Diagnostic applications exist on the net showing system information. This is a last resort if you don't have Microsoft Office installed, or for some reason or another your System Information app or Regedit fails.
• Download GetWinVersion from here.
• Run GetWinVersion app and click on "Get Win Version".

Done!

If you are still unable to view your Build Number after following the first few suggestions on top, try the diagnostic application Everest Ultimate Edition by Lavalys. The software contains useful diagnostic information, and shows the Windows Build on the Operating System Tab among others.

• You can download the Trial Version here and just uninstall after you’ve taken note of the Build Number.

Cheers!