How do I check if I have an EFI partition on my computer?

Question

I know how to look up the partitions on my system using Disk Management and diskpart in the command line. But how can I tell if I have an EFI partition? I am using Windows 7 and I see there is a 100 MB System Reserved partition, but I don't know if that is the EFI or not

Answer 1

The globally unique identifier (GUID) for the EFI System partition in the GUID Partition Table (GPT) scheme is C12A7328-F81F-11D2-BA4B-00A0C93EC93B, while its ID in the MBR partition table scheme is 0xEF. You can view the GUID using the diskpart utility by selecting the disk, e.g. select disk 0, then the relevant partition, e.g., select partition 2, and then issuing the command detail partition. If the type value shown for the partition is C12A7328-F81F-11D2-BA4B-00A0C93EC93B, then it is the EFI System Partition (ESP) - see EFI System Partition for an example.

Answer 2

If you see a 100MB system reserved partition, then you do not have an EFI partition and your computer is in legacy BIOS mode. If you had an EFI partition, both Disk Management and diskpart would tell you so.

EFI partitions are found on GPT formatted drives and are used to boot the operating system. Although the UEFI spec and the GPT partitioning scheme are independent of one another, Windows requires that you use them together. You cannot boot Windows from an MBR formatted disk on a UEFI system, and you cannot boot from a GPT disk on a legacy BIOS system. That's how I know how your system is configured.