Calculator
Windows Server license calculator: core packs and CALs
Windows Server Standard
- Times all cores are licensed
- 1
- Core licences in total
- 16
1 × 16-core pack + 0 × 2-core pack
Windows Server Datacenter
- Unlimited virtual machines
- ∞
- Core licences in total
- 16
1 × 16-core pack + 0 × 2-core pack
Client Access Licences (CALs)
- User CALs (per person)
- 20
- Device CALs (per device)
- 15
Device CALs need fewer licences: 1 × 10-CAL pack + 5 × single licences
Users and devices fit the Essentials limit (25 users, 50 devices).
The result estimates licence counts under Microsoft rules and is not legal advice. It does not cover RDS CALs, External Connector or SQL Server.
What the calculator is for
Licensing Windows Server means counting several things at once: cores with minimums, the number of virtual machines, and access licences. The calculator does this for you and shows the result in packs of 2 and 16 cores, the way they are sold. The general rules are on the Windows Server license page.
How the calculator counts
The rules it applies:
- Cores per processor. For each processor it uses the larger of 8 or its number of cores.
- Server minimum. The server total is at least 16. The result is rounded up to an even number.
- Standard. A licence covers two virtual machines. For every further two machines, all cores are licensed again.
- Datacenter. The number of virtual machines is unlimited, so licensing all cores once is enough.
- CALs. It compares the number of users with the number of devices and gives the smaller one, because that many licences suffice.
- Essentials. The edition includes CALs for up to 25 users and 50 devices. Above those limits the calculator does not suggest Essentials.
Example: two 12-core processors and 5 virtual machines
The server has 2 processors with 12 cores each, so 24 cores. Each processor has more than 8 cores and the total exceeds 16, so the minimums do not change the result.
| Edition | Core licences needed | Packs |
|---|---|---|
| Standard, 5 virtual machines | 24 cores × 3 rounds (2 machines each) = 72 core licences | 4 packs of 16 cores and 4 packs of 2 cores |
| Datacenter | 24 core licences | 1 pack of 16 cores and 4 packs of 2 cores |
The three rounds in Standard come from splitting 5 machines into groups of 2, rounded up.
Frequently asked questions
Short answers to the questions we hear most often.
Does the calculator apply the 16-core server minimum?
Yes. It counts at least 8 cores per processor and at least 16 per server, then rounds up to an even number.
Why does Standard need more licences than cores?
One Standard licence covers two virtual machines. With more machines, all cores are licensed again for every further two.
How many CALs do I need?
The smaller of two numbers: the users or the devices that connect to the server. Essentials includes CALs for up to 25 users and 50 devices.
Is the calculator result binding?
No. It is a planning estimate. Microsoft's licence terms are what count.
Legal basis and sources
We checked licensing rules and support dates against official documents. Links open the publishers’ pages.
Licences for your company?
Business account, quotes on request and invoices in your customer panel.
