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Learn the Secrets of the Windows Build Number

Most of you probably never even think about the Windows build number — after all, it’s not something you see very often, and it doesn’t matter. But it does hold an interesting secret since Windows Vista.

You can see the build number by opening up a command prompt, which will display the build number right at the top of the window. You can also see it in a couple of dialog windows throughout the Control Panel, but the command prompt is the easiest way to get to it.

Microsoft has a history of doing fun things with their build numbers — Windows 95′s build number was 950, Windows 98′s build number was 1998, Windows 98 SE was 2222, and Windows XP was 2600, a reference to the hacker magazine.

Starting with Windows Vista, they started doing things a little differently, at least. Here are the last few build numbers:

Windows 8 – 6.2.9200
Windows 7 – 6.1.7600
Windows Vista – 6.0.6000

Notice anything interesting about those numbers? First, the build number has increased by exactly 1600 each time. Secondly, each number is exactly divisible by 16.

It turns out that Microsoft’s developer team made the requirement since Vista that each build be evenly divisible so that they could use the bottom four bits of the number for internal purposes. The Windows 8 developers wanted to use 8888 as the build number for Windows 8, but they couldn’t, because it isn’t evenly divisible by 16, so they ended up using the next available number that seemed somewhat fun, 9200 — likely because it was exactly 1600 more than the previous one.

There’s no way to tell what the next version of Windows is going to bring — there’s a lot of talk about Microsoft switching to a quicker update schedule, with new versions of Windows on a regular basis. Just do a search for Windows Blue to see the rumor mill at work.

So whenever the next Windows update comes down, check the build number. It should be divisible by 16.

Lowell Heddings, better known online as the How-To Geek, spends all his free time bringing you fresh geekery on a daily basis. You can follow him on if you'd like.

  • Published 03/16/13

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