The amount of memory that you allocate for a virtual machine is the amount of memory that the guest operating system detects.

The minimum memory size is 4 MB for virtual machines that use BIOS firmware. Virtual machines that use EFI firmware require at least 96 MB of RAM or they cannot power on.

The maximum memory size for a virtual machine depends on the host's physical memory and the virtual machine's hardware version.

If the virtual machine memory is greater than the host memory size, swapping occurs, which can have a severe effect on virtual machine performance. The memory size must be a multiple of 4 MB. The maximum for best performance represents the threshold above which the host’s physical memory is insufficient to run the virtual machine at full speed. This value fluctuates as conditions on the host change, for example, as virtual machines are powered on or off.

Table 1. Maximum Virtual Machine Memory
Introduced in Host Version Virtual Machine Version Maximum Memory Size
ESXi 6.0 11 4080 GB
ESXi 5.5 10 1011 GB
ESXi 5.1 9 1011 GB
ESXi 5.0 8 1011 GB
ESX/ESXi 4.x 7 255 GB
ESX/ESXi 3.x 4 65,532 MB

The ESXi host version indicates when support began for the increased memory size. For example, the memory size of a version 7 virtual machine that is running on ESXi 5.0 is restricted to 255 GB.


  1. On the Memory page of the New Virtual Machine wizard, select a size for the virtual memory.
    You can use the slider or use the up and down arrows to select the number. To access the predefined default or recommended setting, click the colored triangles on the right side of the memory bar.
  2. Click Next.
    The Network page opens.

What to do next

Select network adapters for the virtual machine.