Windows Server License Calculator
Estimate Windows Server core licenses and Client Access Licenses (CALs) for your environment — Standard vs Datacenter, virtualization rights, and CAL requirements explained.
Standard vs Datacenter — Which Costs Less for You?
Standard licenses cover up to 2 virtual machines per full license — running more means licensing the same cores again. Datacenter covers unlimited virtual machines per license. Above a certain VM count, Datacenter becomes the cheaper option.
How Windows Server Core Licensing Works
Since Windows Server 2016, Standard and Datacenter editions are licensed per physical core, not per server or per socket. Every physical core must be licensed, subject to two minimums: 8 core licenses per physical processor and 16 core licenses per server, whichever is higher.
Licenses are purchased as 2-core packs or 16-core packs (a 16-core pack is simply 8 two-core packs bundled into a single purchase line — same cost, fewer SKUs to manage). A typical dual-socket server with 8 cores per socket needs exactly one 16-core pack. Denser or multi-socket servers mix packs to match their actual core count.
Standard vs Datacenter Edition
Standard includes rights to run up to 2 Operating System Environments (OSEs) — for example, 2 virtual machines, or 1 physical instance plus 1 virtual machine — for each full set of core licenses covering the server. Need more VMs on Standard? You license the same physical cores again to unlock another 2 OSEs.
Datacenter includes unlimited virtualization rights per full set of core licenses, plus Datacenter-only features like Storage Spaces Direct, Storage Replica, and Shielded VMs. It costs more per core, but becomes more economical once a host needs to run many VMs.
Do I Need CALs?
A Client Access License is required for each user or device that accesses Windows Server services — file and print sharing, authentication, and other core server roles. You choose per-user (one CAL per person, regardless of how many devices they use) or per-device (one CAL per device, regardless of how many people use it) — pick whichever fits your ratio of users to devices best.
What About Remote Desktop Services?
If staff connect to a session host for remote desktops or RemoteApp (common for shared terminal-style access), you need RDS CALs in addition to standard Server CALs — RDS CALs are licensed separately and are not included in the base Windows Server license.
Not Sure Which Licensing Path Fits Your Environment?
Server licensing has real edge cases — Software Assurance, Azure Hybrid Benefit, CSP vs EA pricing, and virtualization density all affect the right answer. Decoding IT can review your environment and quote exact licensing, sized correctly the first time.