Windows Server Versions and Lifecycle: Release and End-of-Support Dates

The latest version of Windows Server is Windows Server 2025, generally available since 1 November 2024 and in mainstream support until 13 November 2029. As of 5 November 2026, four versions are supported: Windows Server 2025 in mainstream support, and Windows Server 2022, 2019 and 2016 in extended support, which for 2016 ends on 12 January 2027. Every older version, including 2012 and 2012 R2, whose paid Extended Security Updates ended on 13 October 2026, receives no security updates at all.

This reference, compiled by LICENSEWARE from Microsoft’s lifecycle pages, lists every Windows Server version from 2008 to 2025 with its build number, release and end-of-support dates and licensing model, then covers how to check which version a server runs, what end of support means for licensing and audits, and how to plan the next upgrade.

Windows Server versions and support dates

Dates are the last day of each phase as Microsoft’s lifecycle pages give them (Pacific Time). Mainstream support brings security and non-security fixes; extended support brings security updates only; Extended Security Updates (ESU) are a paid add-on of up to three years after extended support ends.

Sources: Microsoft Learn’s Windows Server 2025 lifecycle, Windows Server 2022 lifecycle, Windows Server 2019 lifecycle, Windows Server 2016 lifecycle, Windows Server 2012 R2 lifecycle, Windows Server 2012 lifecycle, Windows Server 2008 R2 lifecycle and Windows Server 2008 lifecycle pages, the Extended Security Updates lifecycle FAQ and the Windows Server release information page for the 2016 to 2025 build numbers. Builds for 2008 R2 to 2012 R2 are the OS version numbers Microsoft prints for those releases (6.1.7601, 6.2.9200, 6.3.9600); Windows Server 2008 is operating system version 6.0. Essentials editions follow the same dates as their version.

Between 2017 and 2022 Microsoft also shipped Semi-Annual Channel releases (versions 1709 to 20H2) with 18 months of support each; the channel was retired on 9 August 2022 and replaced by the Windows Server Annual Channel, Datacenter only, under the Modern Lifecycle Policy.

How to check which Windows Server version you run

The build number is the reliable identifier: 26100 is Windows Server 2025, 20348 is 2022, 17763 is 2019 and 14393 is 2016. Three built-in tools show it.

winver

Run winver from the Start menu or a command prompt. The About Windows dialog shows the product name, the version and the OS build. It needs a desktop session, so it suits one server, not an estate.

PowerShell

Get-ComputerInfo returns the operating system name, version and build. To limit the output to the fields that matter:

Get-ComputerInfo -Property OsName, OsVersion, OsBuildNumber

OsName reads, for example, “Microsoft Windows Server 2022 Datacenter”, which also gives the edition, and OsBuildNumber the build. The same facts come from Get-CimInstance Win32_OperatingSystem | Select-Object Caption, Version, BuildNumber, which also runs against remote computers with -ComputerName.

systeminfo

From a command prompt, systeminfo prints the OS name and version among its other lines. To keep only those:

systeminfo | findstr /B /C:"OS Name" /C:"OS Version"

None of these scales to hundreds of servers, and none records what a server ran last quarter. An inventory that collects the edition and build from every server, physical and virtual, is the dependable source.

What end of support means for licensing and audits

End of support stops updates. It does not end the licence. A server running Windows Server 2012 R2 today still needs its Windows Server licence and its CALs, and an audit counts it like any other installation. What changes is the cost of staying put and the rights you need to move.

Extended Security Updates

ESU is Microsoft’s paid bridge for up to three years after extended support ends. According to the ESU lifecycle FAQ:

• In Azure, ESU is included at no extra charge for Windows Server VMs on Azure Virtual Machines, Dedicated Host, Azure VMware Solution, Nutanix Cloud Clusters on Azure and Azure Stack HCI. Software Assurance is not needed for the free ESU, only for Azure Hybrid Benefit.
• On premises or at a hoster, ESU is bought either through Azure Arc, billed monthly, or as yearly ESU licences in a commercial licensing program. Either way the servers must be covered by active Software Assurance or subscription licences, or be licence-included through SPLA.
• Through Azure Arc, ESU is counted per virtual core (8-core minimum per VM, Standard rate) or per physical core (16-core minimum per server; a Standard host covers two VMs, Datacenter all of them). Enrolling late back-bills every month missed since end of support.
• As commercial licences, each ESU year costs the full licence price of the server, and year 2 or 3 can only be bought with the years before it. The ESU core count and edition must match how the server is licensed.
• CALs need active Software Assurance or subscription too: the users and devices that access an ESU-covered server must be covered, although ESU itself is not sold for CALs.

For Windows Server 2016, extended support ends on 12 January 2027, and the ESU FAQ lists no ESU program for it as of this writing. Plan as if there is none.

Software Assurance and upgrade rights

Software Assurance includes new version rights: with SA active when a new version ships, your existing core licences cover it. Without SA, moving from 2016 or 2019 to 2025 means buying 2025 licences, and CALs must be at the version of the server they access or later, so a server upgrade usually brings a CAL upgrade with it (the Core CAL and Enterprise CAL suites explained).

Downgrade rights

The Microsoft Product Terms for Windows Server allow a licence for the current version to run an earlier version instead. A server licensed for 2025 may run 2022 or 2019; the licence follows the current version’s rules, per core and with matching CALs. Downgrade rights do not bring support back: a downgraded server is only as supported as the version it actually runs.

What an auditor looks for

• Every installed instance, supported or not, matched to a licence of the right edition and core count.
• ESU entitlements that match the cores and edition of the servers taking the updates.
• CALs at the version of the newest server users access, not the version they were bought for.
• Downgraded installations backed by a current-version licence, with proof of the licence.

Editions and licensing per version

From Windows Server 2016 the model is per core: every physical core licensed, at least 8 core licences per processor and 16 per server, plus CALs for users or devices. Standard covers two virtual machines per fully licensed server and Datacenter unlimited virtual machines. Windows Server 2012 and 2012 R2 were licensed per processor, one licence for every two processors, with the same Standard and Datacenter split by virtualisation rights. Windows Server 2008 and 2008 R2 had Standard, Enterprise and Datacenter editions, licensed per server or per processor.

The detail, and the list prices, sit in our guides rather than here:

• Windows Server 2025 licensing guide: editions, core rules, CALs and the pay-as-you-go option through Azure Arc.
• Windows Server 2022 licensing guide: the same rules as they applied to 2022.
• Windows Server 2022 vs 2025 comparison: what changed between the two, with Microsoft’s list prices.
• Windows Server 2019 vs 2025 comparison: the upgrade path for estates still on 2019.
• Windows Server 2025 Essentials: the small-business edition and its user and device limits.
• Core CAL and Enterprise CAL suites explained: when CALs come in a suite rather than one by one.

Planning Windows Server upgrades

1. Inventory first. List every server with its version, edition, build and core count, including VMs, hosts and DR copies.
2. Sort by date. Windows Server 2016 ends on 12 January 2027; 2012, 2012 R2, 2008 and 2008 R2 are already past every support date and ESU end.
3. Check SA and subscriptions. They decide whether the upgrade is covered by new version rights and whether ESU can be bought at all.
4. Count CALs. Users and devices need CALs at the version of the newest server they access.
5. Pick the target version. Upgrading to 2025 gives the longest runway, to November 2029 for mainstream support and November 2034 for extended support.
6. Decide about servers that cannot move in time. Migrate them to Azure, where ESU is included, buy ESU where it exists, or isolate and retire them.
7. Keep the evidence. Licence proofs, downgrade use and ESU entitlements, in the form an auditor will ask for.

LICENSEWARE’s Software Inventory Manager collects the Windows Server version, edition and build from every server in an estate, so the servers still on 2016, or older, show up before the end-of-support date does.