Server 1
Physical cores, not threads.
0 if Windows Server runs on the hardware.
On this server Datacenter costs less than Standard from 11 VMs.
Free tool
Windows Server 2025 core license calculator
Enter your servers and the VMs each one runs. See the core licenses, packs and CALs that Standard and Datacenter need, and which one costs less.
Your servers
One card for each physical server or host. The lower-cost way to license each one is picked for you; pick another to compare.
Who connects to these servers
Standard and Datacenter also need a client access license (CAL) for each user or device, whichever way the cores are licensed.
Employees and onsite contractors who use the servers.
Microsoft counts these as CAL equivalents.
Each also needs an RDS CAL.
This calculator uses Microsoft’s public rules. The scan uses your tenant.
A free, read-only Sentsai scan checks your Microsoft 365 tenant for unassigned, idle and duplicated licenses, and licenses still assigned to disabled accounts, with results in minutes.
How Windows Server 2025 is licensed
- Every physical core, with minimums. Standard and Datacenter are licensed per core. Count every physical core in the server, even disabled ones, with at least 8 core licenses for each processor and 16 for the server.12
- Standard covers two VMs at a time. Licensing all the cores once gives Standard two operating system environments (VMs or Hyper-V containers), plus the physical one if it only hosts them. For each further two, license all the cores again. This is called stacking.12
- Datacenter covers any number. Once every core is licensed, Datacenter runs any number of VMs and containers on that server.1
- Or license each VM. With subscription licenses or active Software Assurance you can license a VM by its virtual cores instead, at least 8 per VM and 16 in total, and move those licenses with the VM inside your server farm. The CALs used with those VMs must be subscriptions or have Software Assurance too.13
- Packs of 2 or 16. Core licenses are sold in 2-packs and 16-packs. Eight 2-packs cost the same as one 16-pack and give the same rights, and packs can be split across servers.12
- Access licenses too. Every user or device that uses Standard or Datacenter needs a Windows Server CAL, and Remote Desktop users need an RDS CAL as well. External users can be covered by an External Connector for each server instead. Public web workloads and one server reaching another need none. Microsoft counts Microsoft 365 E3 and E5 user licenses as Windows Server CAL equivalents.12
Core licenses for one server
The core licenses to license a server once: Standard for two VMs, or Datacenter for any number. Servers with fewer cores than the minimums still need 16.
| Cores per processor | 1 processor | 2 processors | 4 processors |
|---|---|---|---|
| 4 | 16 (8 2-packs) | 16 (8 2-packs) | 32 (16 2-packs) |
| 8 | 16 (8 2-packs) | 16 (8 2-packs) | 32 (16 2-packs) |
| 10 | 16 (8 2-packs) | 20 (10 2-packs) | 40 (20 2-packs) |
| 12 | 16 (8 2-packs) | 24 (12 2-packs) | 48 (24 2-packs) |
| 16 | 16 (8 2-packs) | 32 (16 2-packs) | 64 (32 2-packs) |
| 24 | 24 (12 2-packs) | 48 (24 2-packs) | 96 (48 2-packs) |
| 32 | 32 (16 2-packs) | 64 (32 2-packs) | 128 (64 2-packs) |
| 48 | 48 (24 2-packs) | 96 (48 2-packs) | 192 (96 2-packs) |
| 64 | 64 (32 2-packs) | 128 (64 2-packs) | 256 (128 2-packs) |
Standard or Datacenter?
On a 16-core server (two 8-core processors), at Microsoft's suggested retail prices, stacking Standard costs less up to 10 VMs, and Datacenter costs less from 11. Microsoft's own FAQ suggests Datacenter from 13 VMs; the line moves with the prices you pay, so check it against your quote.24
| VMs on the server | Standard core licenses | Standard price | Datacenter price | Lower cost |
|---|---|---|---|---|
| 1 or 2 | 16 | $1,176 | $6,771 | Standard |
| 3 or 4 | 32 | $2,352 | $6,771 | Standard |
| 5 or 6 | 48 | $3,528 | $6,771 | Standard |
| 7 or 8 | 64 | $4,704 | $6,771 | Standard |
| 9 or 10 | 80 | $5,880 | $6,771 | Standard |
| 11 or 12 | 96 | $7,056 | $6,771 | Datacenter |
| 13 or 14 | 112 | $8,232 | $6,771 | Datacenter |
| 15 or 16 | 128 | $9,408 | $6,771 | Datacenter |
Questions people ask
Do I have to license cores I have disabled?
Yes. When you license by physical cores, every core on every processor in the server counts, even if it is switched off.2
Can one server have both Standard and Datacenter licenses?
Not for its physical cores: they must all be licensed with the same version and edition. When you license by VM, each VM can have its own edition or version.2
Can I split a 16-core pack between servers?
Yes. Each core license in a pack can be assigned to a different physical server, as long as each server ends up with enough licenses for its own cores.12
How do I add more VMs to a Standard server?
License all the server's cores again for every further two VMs, step up to Datacenter with Software Assurance, license the extra VMs one by one (subscription or Software Assurance only), or, on Windows Server 2025 connected to Azure Arc, pay as you go for the extra machines.21
What does pay-as-you-go through Azure Arc cost?
Microsoft lists $33.58 per core a month for Windows Server 2025 machines connected to Azure Arc, with no up-front licenses. It suits short-term or burst capacity, and it does not include unlimited virtualization.4
Do Microsoft 365 users still need Windows Server CALs?
Microsoft lists Microsoft 365 E3 and E5 user subscriptions among the licenses that count as Windows Server CAL equivalents, so those users need no separate Windows Server CAL. Remote Desktop needs its own RDS CAL either way. Check the Product Terms for the plan you hold.12
Do Windows Server 2022 CALs cover Windows Server 2025?
No. A CAL covers the same version of Windows Server or earlier ones, so a 2025 server needs 2025 CALs, which also cover 2022 and 2019 servers. When you license by VM, the CALs used with those VMs must be subscriptions or have active Software Assurance too.13
What about Windows Server Essentials?
Essentials is for small businesses with up to 25 users and 50 devices, covers one single-processor server with up to 10 cores and one VM, needs no CALs, and in its 2025 version is sold only preinstalled by server makers.1
Does this calculator cover Azure?
No. In Azure you pay for Windows Server with the VM, or bring licenses with Software Assurance under the Azure Hybrid Benefit, which has its own rules for how many virtual cores each license covers.2
Sources
- Windows Server 2025 licensing guidanceCore minimums, Standard and Datacenter virtualization rights, stacking, licensing by virtual machine, packs, access licenses and CAL equivalents, and Essentials.
- Windows Server licensing FAQDisabled cores, mixing editions, splitting packs, adding VMs to Standard, when Datacenter is recommended, and Azure.
- Product Terms: Windows Server Standard, Datacenter and EssentialsWhen licensing by virtual machine, the CALs used must also be subscriptions or have active Software Assurance.
- Windows Server 2025 licensing and pricingSuggested retail prices for 16 core licenses of Standard and Datacenter, and the pay-as-you-go price per core through Azure Arc.
More free tools
Built by Sentsai from Microsoft’s published licensing guidance and prices. Sentsai is not affiliated with Microsoft. This is a planning aid, not a statement of your license rights: the Product Terms and your agreement decide those, and Microsoft notes that prices vary by country. Windows Server is a trademark of Microsoft.