How can I create a larger EFI partition during a fresh Windows 11 Pro install

Scott · 2026-09-14T02:38:32-0400

@hsehestedt I'd also like to thank you for this process, worked very well.
Once I got into my new Win 11 install I installed Macrium 8.0 free and
created a fresh backup. I then booted to my Macrium recovery media and
restored my my original C: partition to the new partition layout. Now I have
a larger EFI partition. Thanks again.

SIW2 · 2026-09-14T05:22:48-0400

Once I got into my new Win 11 install...I restored my my original C: partition

That will work but shouldn't be necessary

hsehestedt · 2026-09-14T05:50:04-0400

Scott said:
@hsehestedt I'd also like to thank you for this process, worked very well.
Once I got into my new Win 11 install I installed Macrium 8.0 free and
created a fresh backup. I then booted to my Macrium recovery media and
restored my my original C: partition to the new partition layout. Now I have
a larger EFI partition. Thanks again.

Thanks! Glad that it was helpful.

Celery · 2026-09-14T05:58:58-0400

In my opinion, a home user does not need to create these partitions manually. Windows Setup can create the required partitions automatically when Windows is installed to unallocated space.

Windows 11 Setup currently creates a 200 MB EFI system partition on a drive with a 512-byte logical sector size, as shown in the screenshot. Some OEM installations use a larger EFI system partition, such as 260 MB. The size of an OEM-created ESP by itself does not indicate that the drive uses 4K-native (4Kn) sectors. Microsoft's current deployment guidance specifies a minimum ESP size of 200 MB for 512-native and 512e drives, and 300 MB for 4Kn drives.

The EFI system partition must meet the following minimum size requirements for the storage device type:

512 native / 512e byte sector size: minimum 200 MB

4K native sector size: minimum 300 MB

UEFI/GPT-based hard drive partitions

learn.microsoft.com

Edit: 4Kn drives are uncommon in typical home PCs and are more commonly found in enterprise and datacenter systems. Most consumer drives presented to Windows use a 512-byte logical sector size, including 512e drives.

Windows Setup creates a 16 MB Microsoft Reserved (MSR) partition, not a 128 MB partition. Microsoft's current Windows 11 deployment guidance also specifies 16 MB for the MSR.

jimbo45 · 2026-09-14T06:05:36-0400

Hi there
just delete the partitions and then in command mode create partition efi size= <size in Mib/Mb>

Easiest way to do that is boot Windows install disk, and then select REPAIR WINDOWS -->Command mode and after running diskpart enter command above.

reboot and now install windows

no complex scripts needed. K.I.S.S --Keep it short and simple !!!!!.

(you can also "After the fact" if Windows install re-sizes these but this is more complex but GUI driven so mistakes can be avoided)

boot a stand alone bootable instance of gparted -- it's partition interface should be familiar to any Windows users of bog standard partition managers, and simply move / resize relevant partitions. Note you cant do any resizing of the Ms reserved partition.

mouse click the selected partitions and resize / move at will -- note when making a partition bigger you might have to delete a bit of another partition so the new size fits !!.

Here's what the interface looks like -- shouldn't be ANY problem for Windows users.

Ntfs / fat32 partitions handled also perfectly 100% OK with Windows labels for disks e.g C,D,E etc.
Why people PAY for other partition managers to access the features people usually want just beats me every time. Gparted has been around for longer than Windows 10 or 11 has, is 100% free and completely stable

download iso from : GParted -- Download

if you want on a USB stick simple run rufus pointing to the iso - works a treat.

cheers
jimbo

hsehestedt · 2026-09-14T06:08:53-0400

Scott said:
It actually does.

View attachment 182924

But why a MSR partition with 128 MB?

No, list vol does NOT show the disk ID. It shows the volume numbers which is very different. Remember that you may have only a single disk which would have an ID of 0 (zero). But you can have a whole bunch of volumes on that one disk, for example, volumes 0 through 10. That in no way tells you what the disk ID is.

Here is an example. Note that the disk ID is zero but that there are multiple volumes which "list vol" shows. Note too that vol 0 is a mounted ISO image which changes the vol numbers because it preceeds all disk volume numbers!

As for the MSR, I tend to create them larger than necessary. Note that older OSes like Win 7 used 128MB as the default, but Win 10 and 11 use 16MB. Some people still prefer to use 128MB, but it is by no means a necessity.

hsehestedt · 2026-09-14T06:12:38-0400

Celery said:
In my opinion, a home user does not need to create these partitions manually. Windows Setup can create the required partitions automatically when Windows is installed to unallocated space.

That is fine if you are performing a manual installation. If you use unattended setup, it will NOT create the recovery partition last which is the recommended configuration and desired for many reasons. In order to create the partitions in the same manner as a manual installation you MUST explicitly specify partitions be created correctly in your unattended setup.

Celery · 2026-09-14T09:53:28-0400

hsehestedt said:
That is fine if you are performing a manual installation. If you use unattended setup, it will NOT create the recovery partition last which is the recommended configuration and desired for many reasons. In order to create the partitions in the same manner as a manual installation you MUST explicitly specify partitions be created correctly in your unattended setup.

If you use Windows 11 23H2 unattended Setup and a recovery partition has not been defined, Setup does not create a separate recovery partition; instead, the Windows Recovery Environment is placed in C:\Recovery\WindowsRE.

This behavior has changed in newer versions of Windows 11 Setup. With Windows 11 24H2/25H2, if a recovery partition has not been defined in the answer file, Setup can automatically create one at the end of the disk. Therefore, it is not necessary to explicitly create a recovery partition in autounattend.xml to obtain the recommended partition order.

I tested this in a virtual machine using Windows 11 25H2 build 26200.9445 and the following settings in autounattend.xml:

Code:

      <DiskConfiguration>
        <Disk wcm:action="add">
          <DiskID>0</DiskID>
          <WillWipeDisk>true</WillWipeDisk>
          <CreatePartitions>
            <CreatePartition wcm:action="add">
              <Order>1</Order>
              <Type>EFI</Type>
              <Size>500</Size>
            </CreatePartition>
            <CreatePartition wcm:action="add">
              <Order>2</Order>
              <Type>MSR</Type>
              <Size>16</Size>
            </CreatePartition>
            <CreatePartition wcm:action="add">
              <Order>3</Order>
              <Type>Primary</Type>
              <Extend>true</Extend>
            </CreatePartition>
          </CreatePartitions>
          <ModifyPartitions>
            <ModifyPartition wcm:action="add">
              <Order>1</Order>
              <PartitionID>1</PartitionID>
              <Format>FAT32</Format>
            </ModifyPartition>
            <ModifyPartition wcm:action="add">
              <Order>2</Order>
              <PartitionID>3</PartitionID>
              <Format>NTFS</Format>
            </ModifyPartition>
          </ModifyPartitions>
        </Disk>
      </DiskConfiguration>
      <ImageInstall>
          <OSImage>
              <InstallTo>
                  <DiskID>0</DiskID>
                  <PartitionID>3</PartitionID>
              </InstallTo>
          </OSImage>
      </ImageInstall>

As the screenshot below shows, Setup automatically created an 892 MB recovery partition at the end of the disk, even though the partition was not specified in autounattend.xml.

garlin · 2026-09-14T10:17:32-0400

jimbo45 said:
Easiest way to do that is boot Windows install disk, and then select REPAIR WINDOWS -->Command mode and after running diskpart enter command above.

If you're using a clean MCT or Insider ISO, "Repair My PC" has been broken since May 2026. Images created by UUP dump don't have this problem.

The alternative (which always works) is tying Shift-F10 to open a CMD window.

hsehestedt · 2026-09-14T13:26:35-0400

Celery said:
This behavior has changed in newer versions of Windows 11 Setup. With Windows 11 24H2/25H2, if a recovery partition has not been defined in the answer file, Setup can automatically create one at the end of the disk.

Sweet! I was not aware of that. I'll have to update my notes to reflect that, but unfortunately I will still need to create partitions in my answer file since I use larger than default sizes for both the EFI and recovery partitions.

hsehestedt · 2026-09-14T13:55:22-0400

@Celery,

I took a look at your answer file in more detail. I see that you too are creating a larger than default EFI partition so that leaves only the recovery partition for to deal with. I guess that I can use your method, then just run a script at the end of the Windows installation process that basically does this:

reagentc /disable
delete the recovery partition
resize the Windows partition to allow the amount of space I want for the recovery partition
recreate the recovery partition
reagentc /enable

Thanks for the info. I learned something new that will allow me to simplify my answer file.

How can I create a larger EFI partition during a fresh Windows 11 Pro install

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