Licensing SQL Server: per core or server + CAL

Which SQL Server license do you need: per core or server + CAL? Microsoft has two licensing models for SQL Server. Per core you license all processor cores of the server, with at least 4 core licenses per processor; any number of users and devices may then access it. Server + CAL is available for the Standard edition only: one server license per server and one client access license (CAL) per user or device. With few, countable users, server + CAL usually fits; with many or an unknown number of users, the per-core model.

Quick decision

Your situation Suitable model
Few employees, all known by name, one or two servers Server + CAL
The same users access several SQL Servers Server + CAL (one CAL covers all licensed servers)
Public web application, customer portal, users cannot be counted Per core
Many users on a small server Per core
Enterprise edition Per core (server + CAL is no longer available for it)
The free Express is enough (database up to 50 GB, 4 cores) No license needed

Whether Express is enough is covered in the guide
SQL Server Express: limits. The differences between Express, Standard and Enterprise are covered in the guide
SQL Server 2025: editions compared; this page only explains the licensing models.

The two models compared

Feature Per core Server + CAL
Available for Standard and Enterprise Standard only
What is licensed every physical processor core of the server the server and every accessing user or device
Minimum quantity 4 core licenses per processor 1 server license per server, 1 CAL per user or device
Sales unit packs of 2 core licenses each single server license, single CALs
CALs needed No Yes, also for indirect access
Number of users accessing unlimited as many as there are CALs
External users (customers, partners) covered need CALs as well
Operating system environment and instances any number of instances in the physical operating system environment of the server (Standard) one operating system environment per server license, physical or virtual; any number of instances in it

All information comes from Microsoft’s licensing guide and Product Terms for SQL Server 2025. The two differ on one point: for server + CAL, the licensing guide speaks of one instance per server license. The Product Terms allow one operating system environment per server license and any number of instances in it. We follow the Product Terms.

Per core: how to count

  1. Count the physical cores of all processors in the server. Hyper-threading does not count twice.
  2. At least 4 core licenses apply per processor, even if the processor has fewer cores.
  3. Microsoft sells core licenses in 2-core packs. The total must therefore be an even number.
  4. All cores of the server count, not only those that SQL Server uses. The Standard edition uses at most 32 cores per instance (SQL Server 2025); a server with 48 cores still needs 48 core licenses.
Server Calculation Core licenses
1 processor with 4 cores 4 4
1 processor with 8 cores 8 8
1 processor with 16 cores 16 16
2 processors with 2 cores each 2 × minimum quantity 4 8
2 processors with 12 cores each 2 × 12 24

Server + CAL: how to count

  1. One server license per server on which SQL Server Standard runs. The server is the physical machine. Per server license you may run SQL Server in one operating system environment, physical or virtual. The Product Terms allow any number of instances in it.
  2. One CAL per user or per device that accesses SQL Server. A user CAL covers one person on any number of devices, a device CAL covers one device with any number of people.
  3. Indirect access counts too. If 20 people work with an inventory management system that stores its data in SQL Server, you need 20 CALs. An application server in between or a shared service account does not reduce the number. Microsoft calls this multiplexing.
  4. Devices without an operator, such as measuring stations or checkouts, also need a CAL.
  5. A CAL covers all licensed SQL Servers in the company and the same or an earlier version. For SQL Server 2025 you need version 2025 CALs.

When user CALs and when device CALs are cheaper is explained in the guide
User CAL or device CAL. The principle is the same as for Windows Server; you need SQL Server CALs in addition to the
Windows Server CALs.

The decision rule

Put the quantities side by side and then compare the prices on the product pages:

  • Option A: core licenses for all cores (at least 4 per processor).
  • Option B: 1 server license + CALs for all users or devices.

Option B gets more expensive with every additional user, option A with every additional core. If a second SQL Server is added, you only need one more server license in option B; the existing CALs remain valid. In option A you license the cores of the second server completely anew.

Typical cases

Office with 12 workstations and industry software. One server with one processor and 8 cores, 12 employees. Option A: 8 core licenses. Option B: 1 server license and 12 user CALs. With so few users, option B is usually the smaller bill. Check beforehand whether your software vendor does not approve Express anyway.

Warehouse with shift work. 6 terminals at which 18 people work in three shifts. With device CALs you need 6 CALs instead of 18 user CALs, plus 1 server license.

Customer portal on the internet. The number of users accessing is unknown. Server + CAL is ruled out because every person accessing would need a CAL. A server with one processor and 16 cores needs 16 core licenses.

Growing company, two SQL Servers. 40 employees, two servers with 8 cores each. Option A: 16 core licenses. Option B: 2 server licenses and 40 user CALs. Here an exact price comparison is worthwhile; with every additional employee it shifts toward the per-core model.

Virtual machines and failover servers

Here licenses with and without Software Assurance (SA, a maintenance agreement from Microsoft) differ considerably. According to the licensing guide for SQL Server 2025:

Situation Without SA or subscription With SA or subscription
Per core, licensing an individual virtual machine not possible possible, at least 4 core licenses per virtual machine
Per core, Standard, licensing the physical server instances only in the physical operating system environment the same
Server + CAL one operating system environment per server license, physical or virtual additionally moving the virtual machine within the server farm
Passive failover server not included, separate license needed one passive server for high availability and one for disaster recovery included
Assigning the license to another server after 90 days at the earliest the same; virtual machines may move within the server farm

For Standard without SA in a virtual machine, this in practice leaves the server + CAL model. How the Windows Server license underneath is counted is covered in the guide
Licensing Windows Server: cores.

More guides on server applications

SQL Server

Exchange and SharePoint

Development, Cloud PC and security

SQL Server at VivaKeys

Core licenses (per core, without CALs):

Client access licenses for the server + CAL model, i.e. in addition to an existing server license:

All offers are in the SQL Server category, client access licenses for all server products under CALs. How many cores or CALs your environment needs, we are happy to clarify with you before you order. Just tell us the servers, processors, cores and the number of users or devices.

Frequently asked questions

What does a SQL Server license cost? That depends on the model and the quantity: you pay for core licenses per core, and in the server + CAL model per server and per user or device. Current prices are on the product pages in the
SQL Server category. Express and the Developer editions are free.

How do I license SQL Server in a virtual environment? Individual virtual machines can be licensed per core only with Software Assurance or a subscription, with at least 4 core licenses per virtual machine. Without these additions, the server + CAL model remains for Standard: per server license, SQL Server may run in one operating system environment, physical or virtual.

Is there a calculator for SQL Server licensing? The calculation is short: count the physical cores and round up to at least 4 per processor; that gives the core licenses. For server + CAL you count servers and users or devices. The tables above show typical results. For the Windows Server license underneath there is our
license calculator.

How can I read out or check my SQL Server license? The query SELECT SERVERPROPERTY('Edition') shows the installed edition. SQL Server does not store the licensing model or the number of licenses: according to Microsoft, SERVERPROPERTY('LicenseType') always returns DISABLED. You provide proof with your purchase documents.

How do I enter a product key into an existing installation? Start SQL Server Setup, select the “Maintenance” area in the Installation Center and then “Edition Upgrade”, and enter the product key there. Setup restarts the SQL Server services; plan a maintenance window for this.

Do I need CALs in addition to core licenses? No. In the per-core model, any number of users and devices may access the server, including external ones.

Are CALs for SQL Server 2022 also valid for SQL Server 2025? No. A CAL entitles access to the same or an earlier version. Version 2025 CALs, in contrast, also cover SQL Server 2022 and earlier.

Sources

Checked on 2026-11-10 against the publisher’s information:

Cookies and Google services

With your consent we use Google Analytics (statistics) as well as Google's rating widget and Customer Reviews (Google services). In doing so, data is sent to Google, including to the USA. Declining has no disadvantages; you can change your choice at any time under “Cookie settings” in the page footer. Privacy policy