Recommended Size of EFI Partition V1709

  1. Posts : 27,666
    Windows 10 Pro x64 Version 21H1

    Recommended Size of EFI Partition V1709

    I recently built a machine and have noticed that my EFI partition size is 100MB. I clean installed with V1703 and subsequently upgrade to V1709

    Reading the threads (some in forum and some on web) there seems to be a lot of noise that the EFI partition should be 500+ MB.

    In this article it says the minimum is 100MB, dated May 2017.

    As the build is new I thought I would address any size issues now rather than later.

    Does anyone have a link to a MS technical document that states a recommended EFI size? (not the minimum size)

      My Computer

  2. Posts : 17,370
    Windows 11 Pro

    The size provided by Microsoft's script in this article is 100mb:
    UEFI/GPT-based hard drive partitions | Microsoft Docs

    I've had no issues with 100mb EFI system partitions.
      My Computer

  3. Posts : 27,666
    Windows 10 Pro x64 Version 21H1
    Thread Starter

    Thank you NavyLCDR.

    That is the same article I posted with minimum.

    Are you dual booting anything? Pretty sure you are are as I've seen posting where you have Macrium (I think) at end of your disk.
      My Computer

  4. Posts : 17,370
    Windows 11 Pro

    Yes, dual booting Windows 10 Pro and Education on my laptop. On my desktop at home I am booting Windows 10 Pro, Windows 7 Pro, and Windows 7 Home Premium. When you add a different OS to the boot menu which runs from the BCD, it only adds a few lines of text to the BCD and only consumes a few addition bytes - not even 1K more.

    According to MiniTool, my EFI System Partition has 29.4 MB used out of 101 MB and that is dual booting - with a third menu option to boot into Kyhi's Recovery Tools from a second installed hard drive.
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  5. Posts : 27,666
    Windows 10 Pro x64 Version 21H1
    Thread Starter


    Made by life a whole lot easier. Had a crazy plan developed to resize and moving 16MB MSR was a real issue.

    Thanks again.
      My Computer

  6. Posts : 39,996
    windows 10 professional version 1607 build 14393.969 64 bit

    The default size of the EFI partition is now 100 MB.

    The size of the EFI partition was chosen by Microsoft as a size that should be able to allow sufficient space for:
    BIOS firmware
    BIOS updates
    computer manufacturer firmware/software

    There are firmware/software that are installed into the the EFI partition instead of the data drive.
    Over time the free space within the EFI partition decreases with BIOS updates.
    When it comes time to Windows upgrades it will need a certain amount of free space within the EFI partition.

    On a custom computer there should not be any problems with a Windows upgrade related to the size of the EFI or MSR partition.

    Windows upgrade failures related to EFI or MSR partition free space are more common in non-custom computers that have had multiple bios upgrades or software/firmware installed in the EFI partition.
      My Computer

  7. Posts : 27,666
    Windows 10 Pro x64 Version 21H1
    Thread Starter

    Thanks zbook. Solid technical information.
      My Computer


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