Windows Server 2025 Licensing Guide
Cores, CALs and virtual machines explained
By Atif H., CEO, AME Enterprise
Windows Server 2025 is licensed by the number of processor cores, plus Client Access Licences (CALs) for the people or devices that connect. This guide explains the rules in plain language.
Step 1: License every core
- Every physical processor needs at least 8 core licences.
- Every server needs at least 16 core licences.
- Cores are sold in packs (for example 2-core or 16-core packs).
- All physical cores in the server must be licensed.
Step 2: Add CALs
A CAL lets a user or device connect to a Windows Server. A User CAL covers one named user on any device. A Device CAL covers one device used by any number of users. Remote Desktop Services needs separate RDS CALs. The CAL version must be the same as or newer than the server version.
Standard vs Datacenter
- Standard: includes rights for two virtual machines on a fully licensed server. You can add more by licensing the cores again.
- Datacenter: unlimited virtual machines on the licensed server, best for heavy virtualisation.
See Windows Server 2025 Standard and Windows Server 2025 Datacenter.
Example
A server with one 8-core processor still needs 16 core licences. If 10 staff use it, add 10 User CALs. If you run only two virtual machines, Standard is enough.
Upgrading from an older server
Running Server 2016? Read Windows Server 2016 end of life. Buying for a company? See our business pricing.
Frequently asked questions
How is Windows Server 2025 licensed?
By physical core, with a minimum of 8 cores per processor and 16 per server, plus CALs for the users or devices that connect.
What does a 1 user CAL mean for Windows Server 2025?
A User CAL lets one named user access the server from any number of devices. A Device CAL covers one device for any number of users.
Do I need RDS CALs?
Yes, if users connect through Remote Desktop Services. RDS CALs are separate from the standard Windows Server CALs.
What is the difference between Standard and Datacenter?
Standard includes two virtual machines per licensed server. Datacenter includes unlimited virtual machines.
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