Microsoft Windows Server Buyers Guide
How do I know which version I need?
Windows Server 2025 is the current server operating system from Microsoft, released in November 2024 and supported until October 2034. Windows Server 2022 remains widely deployed and is supported until October 2031, so both are safe purchases today. Each version comes in editions that scale from a small office server to a full datacenter — Essentials (2022 only), Standard and Datacenter. The version decides how modern the platform is; the edition decides how much virtualisation you are allowed.
What’s new in Windows Server 2025?
The headline feature is hotpatching: security updates can be applied without rebooting, cutting scheduled downtime dramatically. SMB over QUIC — secure file access over the internet without a VPN — is now included in both Standard and Datacenter (in 2022 it was reserved for the Azure edition). Active Directory gets its biggest update in years with a larger database page size and stronger LDAP security, storage is markedly faster on NVMe drives, and Hyper-V adds GPU partitioning so virtual machines can share a graphics card. If you are buying new hardware today, 2025 is the natural choice; if you are adding capacity to an existing 2022 estate, staying on 2022 keeps everything on one version.
Essentials Edition
With up to 25 users or 50 devices, the Essentials edition is the perfect server OS for small businesses — and uniquely, it needs no CALs at all. It includes many of the features of the larger editions, such as Windows Admin Centre and System Insights, but is limited to a single CPU with a maximum of 10 cores. Essentials is available for Windows Server 2022; for 2025, Microsoft supplies Essentials only through server hardware manufacturers, so Standard is the entry point for a 2025 purchase.
Standard Edition
Standard edition is aimed at physical deployments or light virtualisation. In addition to installation on the physical hardware, the licence covers two virtual machines running Windows Server, with no limit on Linux VMs. Nearly all features and server roles from the Datacenter edition are included — and in 2025 that now covers SMB over QUIC and hotpatching too. The main exceptions remain software-defined storage (Storage Spaces Direct) and unlimited virtualisation, which stay Datacenter-only.
Datacenter Edition
With the Datacenter edition, users have the greatest possible flexibility in server deployment and can realise large, rapidly changing workloads. The number of Windows Server VMs is unlimited and software-defined storage can be implemented using Storage Spaces Direct. If you run more than a handful of Windows VMs per host, Datacenter usually pays for itself.
How does the licensing actually work?
Standard and Datacenter are licensed per physical CPU core: every core in the server must be licensed, with a minimum of 16 cores per server and 8 per CPU. You buy a 16-core or 24-core base licence, then top up with additional-core packs to match your hardware. On top of that, every user or device that accesses the server needs a Client Access Licence (CAL), and anyone using Remote Desktop sessions needs an RDS CAL as well — our CAL guide explains the details. Rather do it the easy way? Use the licensing calculator below — tell it your hardware and head-count and it will build the exact basket for you.
Editions at a glance
| Edition | Ideal for | Licensing model | CAL requirements |
|---|---|---|---|
ESSENTIALS 2022 · 2025 via OEM only | Small businesses with up to 25 users and 50 devices | Single licence, one CPU up to 10 cores | No CALs required |
STANDARD | Physical servers or light virtualisation (2 Windows VMs included) | Per core — all cores licensed, minimum 16 per server | User or Device CAL for every user/device; RDS CALs for remote desktops |
DATACENTER | Highly virtualised datacenters — unlimited Windows Server VMs | Per core — all cores licensed, minimum 16 per server | User or Device CAL for every user/device; RDS CALs for remote desktops |
Windows Server 2022 vs 2025
| Feature | Windows Server 2022 | Windows Server 2025 |
|---|---|---|
| End of support | 14 October 2031 | 10 October 2034 |
| Hotpatching (updates without reboots) | Azure edition only | Standard & Datacenter (Arc-enabled subscription) |
| SMB over QUIC (VPN-less file access) | Azure edition only | Included in Standard & Datacenter |
| Active Directory | 2016 functional level | New 2025 functional level, 32k database pages, stronger LDAP security |
| Storage performance | Standard NVMe stack | Optimised NVMe path — substantially higher IOPS on flash |
| Hyper-V & GPU | GPU passthrough (whole card per VM) | GPU partitioning — one card shared across VMs |
| Licensing model | Per core + CALs | Per core + CALs (unchanged — your CAL counts carry over 1:1) |
Not sure what that means for your bill of materials? The licensing calculator turns your server spec and head-count into an exact basket.
Windows Server & SQL Server licensing calculator
Tell us about your hardware and your people — we will work out which licence packs Microsoft's published rules call for in a typical setup, optionally including SQL Server and SQL CALs, and add them to your basket in one go.