How many licenses does this environment need – and why?

Because Microsoft sets two minimums: at least 8 core licenses per physical processor and at least 16 per physical server – even for a single-processor server. A server with one 8-core processor therefore needs 16 core licenses; the extra eight buy nothing. For procurement that means a 16-core processor costs the same in licenses as an 8-core one.

Standard covers two virtual machines plus the Hyper-V host that only manages the VMs, per full licensing of all cores. Four VMs on a host means licensing all cores twice, six VMs three times. Datacenter licenses the cores once and allows unlimited VMs. The point where Datacenter becomes cheaper depends on the current price of both editions – it sits at a handful of VMs per host, and we name it in the quote with numbers.

Both allow access to every Windows Server in the company; the difference is what gets counted. Per user when staff use several devices – PC, laptop, phone. Per device when several people share one device, for example in shift work or at terminals on a shop floor. The calculator takes the smaller of the two numbers. Mixing is allowed, but every person or device must be covered by one of the two types.

Yes. Every user or device that signs in to a Remote Desktop Session Host needs an RDS CAL in addition to the Windows Server CAL. It is issued by a license server; without one the session host runs for 120 days and then refuses connections. The RDS CAL must match the server version or be newer – a 2022 CAL does not open a 2025 server. Under SPLA, RDS is licensed per user only, as a monthly Subscriber Access License.

No. Every server product has its own access licenses. SQL Server Standard in the Server + CAL model needs a SQL CAL per user or device – even when access runs through an ERP application that uses the database in the background (multiplexing does not change that). Exchange needs a Standard CAL per user or device, the Enterprise CAL is an optional add-on.

Server + CAL exists only for the Standard edition and pays off with few, countable users. Per core is mandatory when users cannot be counted – a website, a web shop, a customer portal – and for the Enterprise edition. Per core, the minimum is four core licenses per VM and per physical processor, sold in two-core packs; a VM with two vCores therefore costs four core licenses.

Windows Server is licensed per core per month and covers access by any number of users – Windows Server CALs are not required. RDS, SQL Server and Exchange are licensed per user per month (SAL), SQL alternatively per core. SPLA is available only to service providers who operate the environment; in our hosted servers the Windows license is included this way. Existing purchased licenses with Software Assurance can be brought in under conditions.

An allocation: which licenses exist (agreements, license statements, for SPLA the monthly invoice) and which servers and users they are assigned to – a license summary like the one from this calculator, with a date. Missing allocation is a finding even when enough licenses were bought. Generate the summary, attach it to the purchase records, repeat it after every change.