Windows Server 2025 Licensing Explained (Core, CAL & Virtualisation)

Windows Server licensing trips up even seasoned IT teams because it combines core-based licensing with Client Access Licenses (CALs). Here's the model without the jargon.

The two things you license

• The server itself — licensed by physical cores (minimum 16 cores per server)
• The users or devices connecting to it — via CALs (User or Device)
• Standard edition — for low-density or physical workloads
• Datacenter edition — for highly virtualised environments with unlimited VMs

Standard vs Datacenter

If you run a handful of VMs, Standard (which grants two VMs per license set) is cheaper. Once you're stacking many VMs per host, Datacenter's unlimited virtualisation rights win on cost.

We size Windows Server licensing correctly the first time so you neither under-license (a compliance risk) nor overspend.