.EFI File Extension

Extensible Firmware Interface File

Developer UEFI Forum
3.9  |  83 Votes

What is an EFI file?

An EFI file is a system file used by Intel-based computer systems and computer devices such as AppleTVs. It contains system-level data that executes between the operating system and the firmware. EFI files are used for staging firmware updates, booting operating systems, and running pre-boot programs.

More Information

Using EFI files, systems can hand off the pre-boot process to a controlled environment. For example, EFI files are sometimes included with firmware updates and are loaded into the device's EFI System partition during the boot process. Here, the executable content in the EFI file safely runs the procedures necessary to update the device.

On systems with installed operating systems, EFI files are stored in hidden, unnamed partitions. For example, Windows 10's EFI file is usually located at one of the following locations:

  • \​EFI\​boot\​bootx64.efi
  • \​EFI\​boot\​bootia32.efi

When you start a PC that does not yet have an installed operating system, the PC searches its disc drives and connected media for an EFI file it can use to boot and install an operating system. For example, the Windows 10 installation package contains the following EFI files, which your PC will search for as it begins installing Windows 10:

  • \​efi\​boot\​bootx64.efi
  • \​efi\​boot\​bootia32.efi

NOTE: The EFI specification, originally developed by Intel, was updated to the UEFI specification, which stands for "Unified Extensible Firmware Interface." The UEFI standard is maintained by the UEFI Forum.

How to open an EFI file

Typically, EFI files are not meant to be opened. Hardware developers and other advanced PC users can open EFI files using the EFI Developer Kit (cross-platform).

Open over 400 file formats with File Viewer Plus.Free Download

Programs that open or reference EFI files


Verified by FileInfo.com

The FileInfo.com team has independently researched the Extensible Firmware Interface file format and Mac, Windows, and Linux apps listed on this page. Our goal is 100% accuracy and we only publish information about file types that we have verified.

If you would like to suggest any additions or updates to this page, please let us know.