Windows Server licence calculator: cores, CALs and RDS
Enter your server and the number of people who use it: the calculator gives the core licences for Standard and Datacenter, the CALs and the RDS CALs, following Microsoft’s licensing rules for Windows Server 2025 and 2022. The calculation runs in your browser.
Six numbers are enough. Results appear as you type; no data is sent.
| Licence | Quantity | Detail |
|---|---|---|
| Core licences to cover | 16 | All physical cores, at least 8 per processor and 16 per server. |
| On the Standard edition | 16 | Cores licensed 1 time(s): the physical server and up to 2 virtual machines. 16-core packs: 1 · 2-core packs: 0. |
| On the Datacenter edition | 16 | Unlimited virtual machines. 16-core packs: 1 · 2-core packs: 0. |
| Windows Server CAL | 10 | Per user: you have fewer people than devices.Per device: you have fewer devices than people. Of the server’s version or newer. |
| RDS CAL | 0 | Per user, on top of the Windows Server CAL. Choose per-device RDS CALs if workstations are shared. |
Our advice: the Standard edition. A single Standard licence covers the physical server and up to 2 virtual machines.
Our advice: the Standard edition, licensed several times. At the US suggested retail price, it is cheaper than Datacenter up to 10 virtual machines. Compare with a Datacenter quote.
Our advice: the Datacenter edition. At the US suggested retail price, it costs less than Standard licensed 6 times, and you can add virtual machines without buying more licences.
Windows Server Essentials may be enough. Your case fits within its limits (25 users, 50 devices, one processor of up to 10 cores) and it needs no CALs. It is sold only with a new server and does not include Remote Desktop for users.
Indicative result, based on the rules published by Microsoft. For an order, a technician checks the quantities with you: request a quote.
How the calculation works
- Core licences: number of processors × cores per processor, with at least 8 per processor and 16 per server, rounded up to an even number (licences are sold in packs of 2 and 16).
- Standard: one licence covers the physical server and 2 virtual machines; for each additional pair of virtual machines, all cores are licensed again.
- Datacenter: all cores licensed once, unlimited virtual machines.
- The Standard or Datacenter advice compares the US suggested retail prices ($1,176 and $6,771 for 16 cores): Datacenter becomes cheaper from 11 virtual machines. Real prices depend on where you buy.
- CALs: the smaller of people and devices, as per-user or per-device CALs. CALs must be of the server’s version or newer.
- RDS CALs: one per person on Remote Desktop, on top of the Windows Server CAL.
- Essentials: suggested if the server has a single processor of up to 10 cores, at most 25 people, 50 devices, 1 virtual machine and no Remote Desktop.
What the calculator does not cover
- External users (customers, partners): one CAL each or one External Connector licence per server.
- Server clusters and moving virtual machines between hosts: each physical server must be licensed for the virtual machines it can run.
- Pay-as-you-go through Azure Arc (Windows Server 2025, $33.58 per core per month in the United States), which follows other rules.
The detailed rules: core and CAL licensing, RDS CALs and Windows Server 2016 end of support.