Windows build checker: is your PC up to date?

Enter your Windows build number to see whether you have the latest security update, how many months behind you are, which update to install, and whether your Windows version still gets updates at all. Works for Windows 10, Windows 11 and Windows Server.

Your build number

Windows 10 / 11 Windows Server

Find it: press Win + R, type winver and press Enter. The build is shown as "OS Build 26100.7171". In PowerShell: (Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion').CurrentBuild plus UBR.

Update history from Microsoft's Windows release health pages, checked 12 Nov 2026. "Months behind" counts monthly security updates (Patch Tuesday, "B" releases) newer than your build.