I often come across texts where a Windows version is referred to as a four digit number, e.g.

Microsoft is urging users of Windows 10 version 1903 to install this month's SSU or 'servicing stack update'

When I do a [System.Environment]::OSVersion.Version command in PowerShell, the version info that comes back is:

Major  Minor  Build  Revision
-----  -----  -----  --------
10     0      17134  0

Now 17134 is way, way higher than 1903, and from the article date, today, it doesn't seem like 1903 is just a few thousand builds behind my Windows. Where does this lower, currently 4 digit version number come from?

  • 56
    How do they work? Poorly. The single largest piece of code in one of my programs is the function that tries to figure out what version of Windows the user has -- it does everything short of reading chicken entrails to figure it out.
    – Mark
    Jul 11, 2019 at 20:34
  • 11
    It's just like Ubuntu 19.04.
    – user541686
    Jul 12, 2019 at 3:40
  • 2
    ...Why not call the numerous Win32 API's to get the version? Alarming that's the biggest piece of code...
    – user9993
    Jul 12, 2019 at 23:26
  • 4
    This is what happens when you let marketing people make technical decisions. Jul 13, 2019 at 4:36
  • 10
    @user9993 I imagine that he does. I certainly do. Problem is, the Windows APIs lie to you, so if you want to cut through the lies and get the actual version number, then you need to jump through an awful lot of hoops. One could argue, of course, that the real code smell is that your application cares what the real Windows version is. Feature detection is always preferred over version sniffing. But there are a few reasons you really want to know: for example, instrumentation for error reporting. Jul 13, 2019 at 5:24

2 Answers 2


1903: 19 refers to the year 2019 and 03 refers to the month. Similarly, last year in 2018 we had 1803 and 1809, so 1803 was scheduled to be released around March (03) and 1809 was supposed to come around September (09) but got delayed a lot because of the file deleting bugs and other issues.

Regarding the 17134, that is just the build number which you can check by Winkey + R, then type "winver" and it will display your version (1903) and your build number. Two people might be using the same Windows 10 version (such as 1903) but could have different build numbers based upon their most recently installed Windows cumulative update.

  • 6
    The build number does, however, change when you install each month's cumulative update. (This doesn't happen in Windows 7.) Jul 12, 2019 at 5:04
  • It doesn't. I don't know how the information on this reply is considered accurate. Build number is a compilation sequence number mainly used internally at Microsoft, that mainly reveals the state of the installed version, in terms of features. Cumulative updates do not change it. CUs change the revision number, keeping the other number intact. Having said that, usually a new version (whether it's 1903, 22H2 or whatever) tend to go alongside a new build number, because they add some sort of new features. Jan 26, 2023 at 15:16

It is, rather boringly, year:month

It's slightly harder to figure out because they don't always manage to hit the correct month they intended.

From Gaijin.at - Windows Version Numbers

Name / Description          Version Build   Public Release
Windows 10, Version 1507    10.0    10240   2015-07-29  
Windows 10, Version 1511    10.0    10586   2015-11-10  
Windows 10, Version 1607    10.0    14393   2016-08-02  
Windows 10, Version 1703    10.0    15063   2017-04-05  
Windows 10, Version 1709    10.0    16299   2017-10-17  
Windows 10, Version 1803    10.0    17134   2018-04-30  
Windows 10, Version 1809    10.0    17763   2018-11-13  
Windows 10, Version 1903    10.0    18362   2019-05-21
  • 33
    “Don’t always manage to hit the correct month” - in fact they haven’t hit the correct month since 2015!
    – Tim
    Jul 12, 2019 at 7:15
  • 5
    IT minute, opposite of a New York minute
    – Hong Ooi
    Jul 12, 2019 at 7:27
  • 3
    @PierreArlaud, 1903 has 2 month timezone offset then
    – user28434
    Jul 12, 2019 at 14:05
  • 2
    @Tim Eh, might be that the number was set sometime during that month and QA followed, which might add delays. Apart from 1803/1809/1903, all releases happened within ca. 2 weeks of the "intended month".
    – Chieron
    Jul 12, 2019 at 14:05
  • 3
    @Chieron sure, but that’s still confusing. Ubuntu manage to hit their monthly release targets with much much better accuracy...
    – Tim
    Jul 12, 2019 at 14:06

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