Understanding Hyper-V Licensing for Migration from VMware

Hyper-V itself is free if you have your Windows Server licensed according to your hardware. That means you need licenses for all the physical cores you’re using. The guests don’t require additional licenses per se, but any guest OS that requires a license still needs one. The cool thing is, if your host is Windows Server Standard, you can run up to two Windows Server Standard VMs without extra licenses. With a Windows Server Datacenter license, there's no limit on the number of Windows guests you can run. Interestingly, even if you don’t have Windows on your host, as long as you possess the proper licenses for a Standard or Datacenter host, you can still run those VMs.

To run Hyper-V, you need to license the host properly. That means you have to purchase regular licenses plus any necessary "additional core" licenses based on the core count of your physical CPU. For instance, if you have a 20-core CPU, you'd need a Windows Server 2025 Standard license for 16 cores plus a 4-core additional license to cover the host. This setup lets you run Windows Server on the host and on two VMs. For more VMs, you'd follow the same licensing process again. Alternatively, with a Datacenter license, you only have to license the host once, which is cheaper for running multiple VMs (usually 8 or more). Keep in mind, if you’re using replicas, they also need to be licensed, even when not in use.

If your host has a Datacenter license, that covers your VMs running on it. Just be aware that licenses are required per 16 cores, so if your host has more cores, you’ll need to pay more.