Windows Server
Windows Server license: cores, CALs and Server 2019
Core-based licensing: the basics
Since Windows Server 2016 you license the physical cores of the processors in a server. Microsoft sets a minimum of 8 core licences per physical processor and a minimum of 16 per server. Licences are sold in packs of 2 cores and 16 cores, so the core count is always rounded up to an even number.
Example: a server with one 6-core processor still needs licences for 16 cores, because that is the per-server minimum. A server with two 12-core processors needs 24 core licences. To work this out for your own hardware, use the Windows Server license calculator.
The 2-core add-on packs are for adding cores on top of a base pack. We offer them for both Standard and Datacenter.
Standard vs Datacenter
Both editions count cores the same way. They differ in how many virtual machines the licence covers.
| Feature | Standard | Datacenter |
|---|---|---|
| Operating system environments (OSEs, in practice virtual machines) | Two, when all physical cores of the server are licensed | Unlimited |
| Minimum core licences | 8 per processor, 16 per server | 8 per processor, 16 per server |
| Typical use | Physical server or a few virtual machines | Heavily virtualised environments |
| CALs | Required in addition | Required in addition |
In Standard, each additional pair of virtual machines requires licensing all the server cores again. The calculator handles this.
CALs: the part that is easy to forget
A server licence alone does not give anyone the right to connect. Under Microsoft licensing terms, all server software access requires CALs. A User CAL lets one user access the server from any device, and a Device CAL lets one device access the server for any user.
The CAL version must be the same as or newer than the server version. A Windows Server 2019 CAL therefore covers access to 2019 servers and earlier ones. For the difference between the two types and worked examples, read What is a Windows Server CAL.
Remote Desktop Services (RDS) needs separate RDS CALs on top of the base CALs. Access by external users (outside your organisation) is covered by a separate External Connector licence. Both cases are outside what our calculator counts.
Windows Server versions and support dates
We offer Windows Server 2019. Newer versions are shown for comparison; we do not sell them.
| Version | Mainstream support | Extended support | In our range |
|---|---|---|---|
| Windows Server 2019 | Ended 9 January 2024 | Until 9 January 2029 | Yes |
| Windows Server 2022 | Ended October 2026 | Until 14 October 2031 | No (see the Windows Server 2022 article) |
| Windows Server 2025 | Until November 2029 | Until November 2034 | No |
After mainstream support ends, a version still gets security updates under extended support. Once that ends, it gets none. A perpetual licence does not expire, but support does.
How to license a server
Count the cores
Add up the physical cores in each processor. Use at least 8 per processor and at least 16 per server.
Choose the edition
Standard suits a physical server and up to two virtual machines. With heavier virtualisation consider Datacenter. For a small business with up to 25 users, check Essentials.
Add core packs
Add 2-core packs to the base licence until every core in the server is covered.
Add CALs
Count the users or devices that connect to the server and use the smaller of the two numbers. The CAL version cannot be older than the server.
Windows Server 2019 in our range
Standard, Datacenter and Essentials editions, extra core packs, and User and Device CALs.
Windows Server 2019 Standard
Windows Server 2019 Datacenter
Windows Server 2019 Essentials
Windows Server 2019 Standard (2 Core Add-On)
Windows Server 2019 Datacenter (2 Core Add-On)
Windows Server 2019 - 1 User CAL
Windows Server 2019 / 10 User CALs
Windows Server 2019 - 1 Device CAL
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Windows Server 2019 / 10 Device CALs
For companies
If you are licensing a server for a company, see also Microsoft licenses for business, where we describe how company accounts work.
Frequently asked questions
Short answers to the questions we hear most often.
How many cores do I need to license for Windows Server?
All physical cores in the server, but at least 8 per processor and at least 16 per server. Cores are licensed in packs of 2 and 16.
Do I need CALs for Windows Server 2019?
Yes. All access to server software requires CALs, except in Essentials, which includes client access licences for up to 25 users and 50 devices.
Can an older CAL be used with a newer server?
No. A CAL permits access to the same or earlier versions of the server software, so the CAL must match or be newer than the server.
Does Windows Server 2019 still get updates?
Yes, under extended support, which Microsoft lists as running until 9 January 2029.
Is a Remote Desktop CAL the same as a normal CAL?
No. An RDS CAL is bought in addition to the base CAL when the server hosts a graphical user interface for remote users.
Legal basis and sources
We checked licensing rules and support dates against official documents. Links open the publishers’ pages.
- Windows Server 2025 licensing guidance (core and CAL rules)Microsoft · microsoft.com
- Windows Server Product TermsMicrosoft · microsoft.com
- Windows Server 2019 EssentialsMicrosoft · microsoft.com
- Windows Server 2019Microsoft Lifecycle · learn.microsoft.com
- Windows Server 2022Microsoft Lifecycle · learn.microsoft.com
- Windows Server 2025Microsoft Lifecycle · learn.microsoft.com
Licences for your company?
Business account, quotes on request and invoices in your customer panel.
