The default memory size for a virtual machine varies depending on the operating system configured for installation. You can change the memory size in the Configuration Editor. Use the slider to set the new memory size.
Memory size is restricted to multiples of 4 megabytes. The maximum possible size is based on the amount of physical memory on the host. You are not allowed to set the virtual machine's memory size to the total host memory amount because the host requires some memory to operate properly. When selecting the memory size, users should be careful not to assign too much memory to a virtual machine because it can adversely affect the performance of other applications on the host, including other virtual machines.
VMware Workstation also restricts the amount of memory reserved for all running virtual machines. This parameter can be set via a slider in the Memory panel under the Settings > Host Reserved Memory... menu. See Memory Preferences for more information on configuring the amount of memory reserved for all running virtual machines.