FREE · NETWORK & IT INFRASTRUCTURE
Virtualization Host Sizing Calculator.
Size hypervisor hosts for your virtual machines from vCPU-to-core ratio, memory, reserved resources and N+1 or N+2 redundancy.
Host
1–2 for databases and latency-sensitive loads, 3–6 for general servers, higher for light desktops.
1.0 = no overcommit, the safe default for production.
- Virtual machines
- 65
- vCPU (with growth)
- 230
- RAM (with growth)
- 960 GB
- Hosts for CPU
- 3
- Hosts for memory
- 3
- Usable storage needed
- 9.16 TB
- vCPU : core with all hosts running
- 1.92 : 1
- RAM used per host with one host down
- 64.5 %
- Sizing by allocation. Measure real usage (CPU ready time, memory active) with your hypervisor tools to refine the ratios.
- Per-core licensing (operating systems, databases, hypervisors) can make fewer, faster cores cheaper overall; check before choosing hosts.
- Storage excludes RAID or replication overhead; add that in the RAID or storage tool.
How to use Virtualization Host Sizing Calculator
List VM groups with count, vCPU, RAM and disk; describe the host, overcommit ratios, reserves and spare hosts.
How it works
vCPU ÷ ratio gives physical cores; RAM ÷ overcommit gives memory; each is divided by the usable capacity of one host at the target utilisation, the larger count wins and spare hosts are added.
Example
65 VMs with 184 vCPU and 768 GB RAM, plus 25 % growth, on 32-core / 512 GB hosts at 4:1 need 3 hosts plus 1 spare.
Questions about Virtualization Host Sizing Calculator
Is Virtualization Host Sizing Calculator free, and do I need an account?
Yes. This tool is free to use in your browser without an account. Processing takes place on your device.
What are the limits and what should I check?
Sizing by allocation, not measured usage. Licensing, NUMA placement and storage performance are not modelled. Everything is calculated in your browser; nothing is sent or probed on the network. Review the result before using it in your work.
Is my input sent to a server?
Your input is processed in your browser and is not uploaded by this tool. Files and pasted text are cleared when the page is refreshed. Normal website requests are still required to load the page and its libraries. Read the privacy explanation.