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Infrastructure & Storage

VM Capacity Calculator

Estimate how many equal virtual machines fit within CPU and memory allocations.

Calculations run in your browser. The tool does not send your inputs to a server.

01Your inputs

Local workspace

Start with the sample below, or enter your own values.

Enter a numeric value using the unit shown in the label.
Enter a numeric value using the unit shown in the label.
Enter a numeric value using the unit shown in the label.
Enter a numeric value using the unit shown in the label.
Enter a numeric value using the unit shown in the label.
Enter the numeric ratio: use 2 for 2:1.

02Your result

Your result will appear here. Choose an action after checking your inputs.

A quick guide

How to use this tool

  1. Check the example and the unit beside each input.
  2. Enter your values and choose Calculate.
  3. Review the result and assumptions, then copy what you need.

Reset example restores the starting values. Clear removes text and number inputs, returns choices to their first valid option, and removes the result.

Reference guide

Explanation and worked examples

The result is the smaller of the CPU and RAM limits. CPU overcommit allows allocation beyond physical cores; it does not create physical processing capacity.

Use in day-to-day IT work

Estimate equal-size VM allocations on one host before checking cluster admission control.

Checks before applying the result

  • With 32 cores, 2:1 CPU allocation, 128 GiB RAM, 8 GiB reserved, and 4-vCPU/8-GiB VMs, the CPU limit is 16 and RAM limit is 15: the result is 15 VMs.
  • This is an allocation ceiling, not a safe workload count. Check peak CPU, NUMA, per-VM overhead, storage latency, licensing and N+1 host-failure headroom separately.
New to the terminology?
IOPS
Input/output operations completed each second.
GiB vs GB
GiB uses powers of 1,024; GB uses powers of 1,000.
Overcommit
Allocating more virtual resources than physically available.

Keep exploring

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