On Windows 7 and newer, Setup uses this directive to set the EstimatedSize value in the Uninstall registry key when possible since the Windows 7 Add/Remove Programs Control Panel (called Program and Features) no longer automatically calculates it. If an UninstallDisplaySize is not set, Setup estimates the size itself by taking the size of all files installed and adding any ExtraDiskSpaceRequired values set. Note: Windows 7 without any service pack only supports the display of values smaller than 4 GB.

Set in bytes. (1048576 bytes = 1 megabyte)

UninstallDisplaySize=1073741824